Implement Shed Tail

src/data/move.ts

@@ -37,6 +37,7 @@ import { SwitchSummonPhase } from "#app/phases/switch-summon-phase";
 import { SpeciesFormChangeRevertWeatherFormTrigger } from "./pokemon-forms";
 import { GameMode } from "#app/game-mode";
 import { applyChallenges, ChallengeType } from "./challenge";
+import { SwitchType } from "#app/enums/switch-type";
 
 export enum MoveCategory {
   PHYSICAL,
@@ -1476,8 +1477,13 @@ export class HalfSacrificialAttr extends MoveEffectAttr {
  * @see {@linkcode apply}
  */
 export class AddSubstituteAttr extends MoveEffectAttr {
-  constructor() {
+  /** The ratio of the user's max HP that is required to apply this effect */
+  private hpCost: number;
+
+  constructor(hpCost: number = 0.25) {
     super(true);
+
+    this.hpCost = hpCost;
   }
 
   /**
@@ -1493,8 +1499,7 @@ export class AddSubstituteAttr extends MoveEffectAttr {
       return false;
     }
 
-    const hpCost = Math.floor(user.getMaxHp() / 4);
+    user.damageAndUpdate(Math.floor(user.getMaxHp() * this.hpCost), HitResult.OTHER, false, true, true);
-    user.damageAndUpdate(hpCost, HitResult.OTHER, false, true, true);
     user.addTag(BattlerTagType.SUBSTITUTE, 0, move.id, user.id);
     return true;
   }
@@ -1507,7 +1512,7 @@ export class AddSubstituteAttr extends MoveEffectAttr {
   }
 
   getCondition(): MoveConditionFunc {
-    return (user, target, move) => !user.getTag(SubstituteTag) && user.hp > Math.floor(user.getMaxHp() / 4) && user.getMaxHp() > 1;
+    return (user, target, move) => !user.getTag(SubstituteTag) && user.hp > Math.floor(user.getMaxHp() * this.hpCost) && user.getMaxHp() > 1;
   }
 
   getFailedText(user: Pokemon, target: Pokemon, move: Move, cancelled: Utils.BooleanHolder): string | null {
@@ -1521,6 +1526,66 @@ export class AddSubstituteAttr extends MoveEffectAttr {
   }
 }
 
+/**
+ * Attribute implementing the effects of {@link https://bulbapedia.bulbagarden.net/wiki/Shed_Tail_(move) | Shed Tail}.
+ * This is essentially a wrapper for two internal attributes: {@linkcode AddSubstituteAttr} which handles creating
+ * a Substitute for the user, and {@linkcode ForceSwitchOutAttr} which forces the user to switch out and transfers the
+ * Substitute to the switched in Pokemon.
+ */
+export class ShedTailAttr extends MoveEffectAttr {
+  private addSubstituteAttr: AddSubstituteAttr;
+  private forceSwitchOutAttr: ForceSwitchOutAttr;
+
+  constructor() {
+    super(true);
+
+    this.addSubstituteAttr = new AddSubstituteAttr(0.5);
+    this.forceSwitchOutAttr = new ForceSwitchOutAttr(true, SwitchType.SHED_TAIL);
+  }
+
+  /**
+   * Has the user put in a substitute, prompt a switch, and transfer the substitute
+   * to the switched in Pokemon.
+   * @param user The {@linkcode Pokemon} using this move
+   * @param target n/a
+   * @param move The move being used (i.e. Shed Tail)
+   * @param args n/a
+   * @returns a `Promise` that resolves `true` if all effects apply successfully; `false` otherwise
+   */
+  override apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
+    if (this.addSubstituteAttr.apply(user, target, move, args)) {
+      return this.forceSwitchOutAttr.apply(user, target, move, args);
+    } else {
+      return false;
+    }
+  }
+
+  /**
+   * The conditions determining whether the move fails.
+   * @returns A function that returns `true` if the move will not fail.
+   */
+  override getCondition(): MoveConditionFunc {
+    return this.addSubstituteAttr.getCondition() && this.forceSwitchOutAttr.getCondition();
+  }
+
+  /**
+   * Gets the text to show when the move fails. Identical to the fail messages for Substitute
+   * @param user The {@linkcode Pokemon} using the move
+   * @param target n/a
+   * @param move n/a
+   * @param cancelled n/a
+   * @returns The string to display upon the move failing. May vary with different fail conditions.
+   */
+  override getFailedText(user: Pokemon, target: Pokemon, move: Move, cancelled: Utils.BooleanHolder): string | null {
+    return this.addSubstituteAttr.getFailedText(user, target, move, cancelled);
+  }
+
+  override getUserBenefitScore(user: Pokemon, target: Pokemon, move: Move): integer {
+    return this.addSubstituteAttr.getUserBenefitScore(user, target, move)
+      + this.forceSwitchOutAttr.getUserBenefitScore(user, target, move);
+  }
+}
+
 export enum MultiHitType {
   _2,
   _2_TO_5,
@@ -5152,9 +5217,9 @@ export class RevivalBlessingAttr extends MoveEffectAttr {
         if (user.scene.currentBattle.double && user.scene.getEnemyParty().length > 1) {
           const allyPokemon = user.getAlly();
           if (slotIndex<=1) {
-            user.scene.unshiftPhase(new SwitchSummonPhase(user.scene, pokemon.getFieldIndex(), slotIndex, false, false, false));
+            user.scene.unshiftPhase(new SwitchSummonPhase(user.scene, SwitchType.SWITCH, pokemon.getFieldIndex(), slotIndex, false, false));
           } else if (allyPokemon.isFainted()) {
-            user.scene.unshiftPhase(new SwitchSummonPhase(user.scene, allyPokemon.getFieldIndex(), slotIndex, false, false, false));
+            user.scene.unshiftPhase(new SwitchSummonPhase(user.scene, SwitchType.SWITCH, allyPokemon.getFieldIndex(), slotIndex, false, false));
           }
         }
         resolve(true);
@@ -5176,47 +5241,45 @@ export class RevivalBlessingAttr extends MoveEffectAttr {
 
 export class ForceSwitchOutAttr extends MoveEffectAttr {
   private user: boolean;
-  private batonPass: boolean;
+  private switchType: SwitchType;
 
-  constructor(user?: boolean, batonPass?: boolean) {
+  constructor(user: boolean = false, switchType: SwitchType = SwitchType.SWITCH) {
     super(false, MoveEffectTrigger.POST_APPLY, false, true);
-    this.user = !!user;
+    this.user = user;
-    this.batonPass = !!batonPass;
+    this.switchType = switchType;
   }
 
   isBatonPass() {
-    return this.batonPass;
+    return this.switchType === SwitchType.BATON_PASS;
   }
 
-  apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): Promise<boolean> {
+  apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
-    return new Promise(resolve => {
+    // Check if the move category is not STATUS or if the switch out condition is not met
+    if (!this.getSwitchOutCondition()(user, target, move)) {
+      return false;
+    }
 
-  	// Check if the move category is not STATUS or if the switch out condition is not met
+  	/**
-      if (!this.getSwitchOutCondition()(user, target, move)) {
+     * Move the switch out logic inside the conditional block
-        return resolve(false);
+  	 * This ensures that the switch out only happens when the conditions are met
-      }
+     */
-
-  	// Move the switch out logic inside the conditional block
-  	// This ensures that the switch out only happens when the conditions are met
 	  const switchOutTarget = this.user ? user : target;
 	  if (switchOutTarget instanceof PlayerPokemon) {
-        switchOutTarget.leaveField(!this.batonPass);
+      switchOutTarget.leaveField(this.switchType === SwitchType.SWITCH);
 
-        if (switchOutTarget.hp > 0) {
+      if (switchOutTarget.hp > 0) {
-          user.scene.prependToPhase(new SwitchPhase(user.scene, switchOutTarget.getFieldIndex(), true, true), MoveEndPhase);
+        user.scene.prependToPhase(new SwitchPhase(user.scene, this.switchType, switchOutTarget.getFieldIndex(), true, true), MoveEndPhase);
-          resolve(true);
+        return true;
-        } else {
+      }
-          resolve(false);
+      return false;
-        }
-	  	return;
 	  } else if (user.scene.currentBattle.battleType !== BattleType.WILD) {
 	  	// Switch out logic for trainer battles
-        switchOutTarget.leaveField(!this.batonPass);
+      switchOutTarget.leaveField(this.switchType === SwitchType.SWITCH);
 
 	  	if (switchOutTarget.hp > 0) {
         // for opponent switching out
-          user.scene.prependToPhase(new SwitchSummonPhase(user.scene, switchOutTarget.getFieldIndex(), (user.scene.currentBattle.trainer ? user.scene.currentBattle.trainer.getNextSummonIndex((switchOutTarget as EnemyPokemon).trainerSlot) : 0), false, this.batonPass, false), MoveEndPhase);
+        user.scene.prependToPhase(new SwitchSummonPhase(user.scene, this.switchType, switchOutTarget.getFieldIndex(), (user.scene.currentBattle.trainer ? user.scene.currentBattle.trainer.getNextSummonIndex((switchOutTarget as EnemyPokemon).trainerSlot) : 0), false, false), MoveEndPhase);
-        }
+      }
 	  } else {
 	    // Switch out logic for everything else (eg: WILD battles)
 	  	switchOutTarget.leaveField(false);
@@ -5224,11 +5287,11 @@ export class ForceSwitchOutAttr extends MoveEffectAttr {
 	  	if (switchOutTarget.hp) {
 	  	  user.scene.queueMessage(i18next.t("moveTriggers:fled", {pokemonName: getPokemonNameWithAffix(switchOutTarget)}), null, true, 500);
 
-          // in double battles redirect potential moves off fled pokemon
+        // in double battles redirect potential moves off fled pokemon
-          if (switchOutTarget.scene.currentBattle.double) {
+        if (switchOutTarget.scene.currentBattle.double) {
-            const allyPokemon = switchOutTarget.getAlly();
+          const allyPokemon = switchOutTarget.getAlly();
-            switchOutTarget.scene.redirectPokemonMoves(switchOutTarget, allyPokemon);
+          switchOutTarget.scene.redirectPokemonMoves(switchOutTarget, allyPokemon);
-          }
+        }
 	  	}
 
 	  	if (!switchOutTarget.getAlly()?.isActive(true)) {
@@ -5241,8 +5304,7 @@ export class ForceSwitchOutAttr extends MoveEffectAttr {
 	  	}
 	  }
 
-	  resolve(true);
+	  return true;
-	  });
   }
 
   getCondition(): MoveConditionFunc {
@@ -5268,8 +5330,8 @@ export class ForceSwitchOutAttr extends MoveEffectAttr {
         return false;
       }
 
-      if (!player && !user.scene.currentBattle.battleType) {
+      if (!player && user.scene.currentBattle.battleType === BattleType.WILD) {
-        if (this.batonPass) {
+        if (this.isBatonPass()) {
           return false;
         }
         // Don't allow wild opponents to flee on the boss stage since it can ruin a run early on
@@ -5288,7 +5350,7 @@ export class ForceSwitchOutAttr extends MoveEffectAttr {
       return -20;
     }
     let ret = this.user ? Math.floor((1 - user.getHpRatio()) * 20) : super.getUserBenefitScore(user, target, move);
-    if (this.user && this.batonPass) {
+    if (this.user && this.isBatonPass()) {
       const statStageTotal = user.getStatStages().reduce((s: integer, total: integer) => total += s, 0);
       ret = ret / 2 + (Phaser.Tweens.Builders.GetEaseFunction("Sine.easeOut")(Math.min(Math.abs(statStageTotal), 10) / 10) * (statStageTotal >= 0 ? 10 : -10));
     }
@@ -7376,7 +7438,7 @@ export function initMoves() {
     new AttackMove(Moves.DRAGON_BREATH, Type.DRAGON, MoveCategory.SPECIAL, 60, 100, 20, 30, 0, 2)
       .attr(StatusEffectAttr, StatusEffect.PARALYSIS),
     new SelfStatusMove(Moves.BATON_PASS, Type.NORMAL, -1, 40, -1, 0, 2)
-      .attr(ForceSwitchOutAttr, true, true)
+      .attr(ForceSwitchOutAttr, true, SwitchType.BATON_PASS)
       .hidesUser(),
     new StatusMove(Moves.ENCORE, Type.NORMAL, 100, 5, -1, 0, 2)
       .attr(AddBattlerTagAttr, BattlerTagType.ENCORE, false, true)
@@ -7801,7 +7863,7 @@ export function initMoves() {
       .makesContact(false)
       .target(MoveTarget.ATTACKER),
     new AttackMove(Moves.U_TURN, Type.BUG, MoveCategory.PHYSICAL, 70, 100, 20, -1, 0, 4)
-      .attr(ForceSwitchOutAttr, true, false),
+      .attr(ForceSwitchOutAttr, true),
     new AttackMove(Moves.CLOSE_COMBAT, Type.FIGHTING, MoveCategory.PHYSICAL, 120, 100, 5, -1, 0, 4)
       .attr(StatStageChangeAttr, [ Stat.DEF, Stat.SPDEF ], -1, true),
     new AttackMove(Moves.PAYBACK, Type.DARK, MoveCategory.PHYSICAL, 50, 100, 10, -1, 0, 4)
@@ -8234,7 +8296,7 @@ export function initMoves() {
     new AttackMove(Moves.GRASS_PLEDGE, Type.GRASS, MoveCategory.SPECIAL, 80, 100, 10, -1, 0, 5)
       .partial(),
     new AttackMove(Moves.VOLT_SWITCH, Type.ELECTRIC, MoveCategory.SPECIAL, 70, 100, 20, -1, 0, 5)
-      .attr(ForceSwitchOutAttr, true, false),
+      .attr(ForceSwitchOutAttr, true),
     new AttackMove(Moves.STRUGGLE_BUG, Type.BUG, MoveCategory.SPECIAL, 50, 100, 20, 100, 0, 5)
       .attr(StatStageChangeAttr, [ Stat.SPATK ], -1)
       .target(MoveTarget.ALL_NEAR_ENEMIES),
@@ -8402,7 +8464,7 @@ export function initMoves() {
       .target(MoveTarget.ALL_NEAR_ENEMIES),
     new StatusMove(Moves.PARTING_SHOT, Type.DARK, 100, 20, -1, 0, 6)
       .attr(StatStageChangeAttr, [ Stat.ATK, Stat.SPATK ], -1, false, null, true, true, MoveEffectTrigger.PRE_APPLY)
-      .attr(ForceSwitchOutAttr, true, false)
+      .attr(ForceSwitchOutAttr, true)
       .soundBased(),
     new StatusMove(Moves.TOPSY_TURVY, Type.DARK, -1, 20, -1, 0, 6)
       .attr(InvertStatsAttr),
@@ -9158,7 +9220,7 @@ export function initMoves() {
       .attr(StatStageChangeAttr, [ Stat.ATK, Stat.DEF ], 1)
       .target(MoveTarget.NEAR_ALLY),
     new AttackMove(Moves.FLIP_TURN, Type.WATER, MoveCategory.PHYSICAL, 60, 100, 20, -1, 0, 8)
-      .attr(ForceSwitchOutAttr, true, false),
+      .attr(ForceSwitchOutAttr, true),
     new AttackMove(Moves.TRIPLE_AXEL, Type.ICE, MoveCategory.PHYSICAL, 20, 90, 10, -1, 0, 8)
       .attr(MultiHitAttr, MultiHitType._3)
       .attr(MultiHitPowerIncrementAttr, 3)
@@ -9485,10 +9547,10 @@ export function initMoves() {
       .attr(MovePowerMultiplierAttr, (user, target, move) => target.getAttackTypeEffectiveness(move.type, user) >= 2 ? 5461/4096 : 1)
       .makesContact(),
     new SelfStatusMove(Moves.SHED_TAIL, Type.NORMAL, -1, 10, -1, 0, 9)
-      .unimplemented(),
+      .attr(ShedTailAttr),
     new StatusMove(Moves.CHILLY_RECEPTION, Type.ICE, -1, 10, -1, 0, 9)
       .attr(WeatherChangeAttr, WeatherType.SNOW)
-      .attr(ForceSwitchOutAttr, true, false)
+      .attr(ForceSwitchOutAttr, true)
       .target(MoveTarget.BOTH_SIDES),
     new SelfStatusMove(Moves.TIDY_UP, Type.NORMAL, -1, 10, -1, 0, 9)
       .attr(StatStageChangeAttr, [ Stat.ATK, Stat.SPD ], 1, true, null, true, true)

src/enums/switch-type.ts

@@ -0,0 +1,12 @@
+/**
+ * Indicates the type of switch functionality that a {@linkcode SwitchPhase}
+ * or {@linkcode SwitchSummonPhase} will carry out.
+ */
+export enum SwitchType {
+  /** Basic switchout where the Pokemon to switch in is selected */
+  SWITCH,
+  /** Transfers stat stages and other effects from the returning Pokemon to the switched in Pokemon */
+  BATON_PASS,
+  /** Transfers the returning Pokemon's Substitute to the switched in Pokemon */
+  SHED_TAIL
+}

src/field/pokemon.ts

@@ -61,6 +61,7 @@ import { Challenges } from "#enums/challenges";
 import { PokemonAnimType } from "#app/enums/pokemon-anim-type";
 import { PLAYER_PARTY_MAX_SIZE } from "#app/constants";
 import { MysteryEncounterPokemonData } from "#app/data/mystery-encounters/mystery-encounter-pokemon-data";
+import { SwitchType } from "#app/enums/switch-type";
 
 export enum FieldPosition {
   CENTER,
@@ -3989,16 +3990,17 @@ export class PlayerPokemon extends Pokemon {
   /**
    * Causes this mon to leave the field (via {@linkcode leaveField}) and then
    * opens the party switcher UI to switch a new mon in
-   * @param batonPass Indicates if this switch was caused by a baton pass (and
+   * @param switchType the {@linkcode SwitchType} for this switch-out. If this is
-   * thus should maintain active mon effects)
+   * `BATON_PASS` or `SHED_TAIL`, this Pokemon's effects are not cleared upon leaving
+   * the field.
    */
-  switchOut(batonPass: boolean): Promise<void> {
+  switchOut(switchType: SwitchType = SwitchType.SWITCH): Promise<void> {
     return new Promise(resolve => {
-      this.leaveField(!batonPass);
+      this.leaveField(switchType === SwitchType.SWITCH);
 
       this.scene.ui.setMode(Mode.PARTY, PartyUiMode.FAINT_SWITCH, this.getFieldIndex(), (slotIndex: integer, option: PartyOption) => {
         if (slotIndex >= this.scene.currentBattle.getBattlerCount() && slotIndex < 6) {
-          this.scene.prependToPhase(new SwitchSummonPhase(this.scene, this.getFieldIndex(), slotIndex, false, batonPass), MoveEndPhase);
+          this.scene.prependToPhase(new SwitchSummonPhase(this.scene, switchType, this.getFieldIndex(), slotIndex, false), MoveEndPhase);
         }
         this.scene.ui.setMode(Mode.MESSAGE).then(resolve);
       }, PartyUiHandler.FilterNonFainted);
@@ -4060,11 +4062,11 @@ export class PlayerPokemon extends Pokemon {
             const allyPokemon = this.getAlly();
             if (slotIndex<=1) {
               // Revived ally pokemon
-              this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, pokemon.getFieldIndex(), slotIndex, false, false, true));
+              this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, SwitchType.SWITCH, pokemon.getFieldIndex(), slotIndex, false, true));
               this.scene.unshiftPhase(new ToggleDoublePositionPhase(this.scene, true));
             } else if (allyPokemon.isFainted()) {
               // Revived party pokemon, and ally pokemon is fainted
-              this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, allyPokemon.getFieldIndex(), slotIndex, false, false, true));
+              this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, SwitchType.SWITCH, allyPokemon.getFieldIndex(), slotIndex, false, true));
               this.scene.unshiftPhase(new ToggleDoublePositionPhase(this.scene, true));
             }
           }

src/phases/check-switch-phase.ts

@@ -8,6 +8,7 @@ import { BattlePhase } from "./battle-phase";
 import { PostSummonPhase } from "./post-summon-phase";
 import { SummonMissingPhase } from "./summon-missing-phase";
 import { SwitchPhase } from "./switch-phase";
+import { SwitchType } from "#app/enums/switch-type";
 
 export class CheckSwitchPhase extends BattlePhase {
   protected fieldIndex: integer;
@@ -50,7 +51,7 @@ export class CheckSwitchPhase extends BattlePhase {
       this.scene.ui.setMode(Mode.CONFIRM, () => {
         this.scene.ui.setMode(Mode.MESSAGE);
         this.scene.tryRemovePhase(p => p instanceof PostSummonPhase && p.player && p.fieldIndex === this.fieldIndex);
-        this.scene.unshiftPhase(new SwitchPhase(this.scene, this.fieldIndex, false, true));
+        this.scene.unshiftPhase(new SwitchPhase(this.scene, SwitchType.SWITCH, this.fieldIndex, false, true));
         this.end();
       }, () => {
         this.scene.ui.setMode(Mode.MESSAGE);

src/phases/faint-phase.ts

@@ -18,6 +18,7 @@ import { GameOverPhase } from "./game-over-phase";
 import { SwitchPhase } from "./switch-phase";
 import { VictoryPhase } from "./victory-phase";
 import { SpeciesFormChangeActiveTrigger } from "#app/data/pokemon-forms";
+import { SwitchType } from "#app/enums/switch-type";
 
 export class FaintPhase extends PokemonPhase {
   private preventEndure: boolean;
@@ -106,14 +107,14 @@ export class FaintPhase extends PokemonPhase {
          * If previous conditions weren't met, and the player has at least 1 legal Pokemon off the field,
          * push a phase that prompts the player to summon a Pokemon from their party.
          */
-        this.scene.pushPhase(new SwitchPhase(this.scene, this.fieldIndex, true, false));
+        this.scene.pushPhase(new SwitchPhase(this.scene, SwitchType.SWITCH, this.fieldIndex, true, false));
       }
     } else {
       this.scene.unshiftPhase(new VictoryPhase(this.scene, this.battlerIndex));
       if ([BattleType.TRAINER, BattleType.MYSTERY_ENCOUNTER].includes(this.scene.currentBattle.battleType)) {
         const hasReservePartyMember = !!this.scene.getEnemyParty().filter(p => p.isActive() && !p.isOnField() && p.trainerSlot === (pokemon as EnemyPokemon).trainerSlot).length;
         if (hasReservePartyMember) {
-          this.scene.pushPhase(new SwitchSummonPhase(this.scene, this.fieldIndex, -1, false, false, false));
+          this.scene.pushPhase(new SwitchSummonPhase(this.scene, SwitchType.SWITCH, this.fieldIndex, -1, false, false));
         }
       }
     }

src/phases/mystery-encounter-phases.ts

@@ -24,6 +24,7 @@ import { NewBattlePhase } from "#app/phases/new-battle-phase";
 import { GameOverPhase } from "#app/phases/game-over-phase";
 import { SwitchPhase } from "#app/phases/switch-phase";
 import { SeenEncounterData } from "#app/data/mystery-encounters/mystery-encounter-save-data";
+import { SwitchType } from "#app/enums/switch-type";
 
 /**
  * Will handle (in order):
@@ -241,7 +242,7 @@ export class MysteryEncounterBattleStartCleanupPhase extends Phase {
     const playerField = this.scene.getPlayerField();
     playerField.forEach((pokemon, i) => {
       if (!pokemon.isAllowedInBattle() && legalPlayerPartyPokemon.length > i) {
-        this.scene.unshiftPhase(new SwitchPhase(this.scene, i, true, false));
+        this.scene.unshiftPhase(new SwitchPhase(this.scene, SwitchType.SWITCH, i, true, false));
       }
     });
 

src/phases/return-phase.ts

@@ -1,10 +1,11 @@
 import BattleScene from "#app/battle-scene";
 import { SpeciesFormChangeActiveTrigger } from "#app/data/pokemon-forms";
+import { SwitchType } from "#app/enums/switch-type";
 import { SwitchSummonPhase } from "./switch-summon-phase";
 
 export class ReturnPhase extends SwitchSummonPhase {
   constructor(scene: BattleScene, fieldIndex: integer) {
-    super(scene, fieldIndex, -1, true, false);
+    super(scene, SwitchType.SWITCH, fieldIndex, -1, true, false);
   }
 
   switchAndSummon(): void {

src/phases/switch-phase.ts

@@ -1,4 +1,5 @@
 import BattleScene from "#app/battle-scene";
+import { SwitchType } from "#app/enums/switch-type";
 import PartyUiHandler, { PartyUiMode, PartyOption } from "#app/ui/party-ui-handler";
 import { Mode } from "#app/ui/ui";
 import { BattlePhase } from "./battle-phase";
@@ -10,21 +11,24 @@ import { SwitchSummonPhase } from "./switch-summon-phase";
  */
 export class SwitchPhase extends BattlePhase {
   protected fieldIndex: integer;
+  private switchType: SwitchType;
   private isModal: boolean;
   private doReturn: boolean;
 
   /**
      * Creates a new SwitchPhase
      * @param scene {@linkcode BattleScene} Current battle scene
+     * @param switchType The type of switch logic this phase implements
      * @param fieldIndex Field index to switch out
      * @param isModal Indicates if the switch should be forced (true) or is
      * optional (false).
      * @param doReturn Indicates if the party member on the field should be
      * recalled to ball or has already left the field. Passed to {@linkcode SwitchSummonPhase}.
      */
-  constructor(scene: BattleScene, fieldIndex: integer, isModal: boolean, doReturn: boolean) {
+  constructor(scene: BattleScene, switchType: SwitchType, fieldIndex: integer, isModal: boolean, doReturn: boolean) {
     super(scene);
 
+    this.switchType = switchType;
     this.fieldIndex = fieldIndex;
     this.isModal = isModal;
     this.doReturn = doReturn;
@@ -38,11 +42,13 @@ export class SwitchPhase extends BattlePhase {
       return super.end();
     }
 
-    // Skip if the fainted party member has been revived already. doReturn is
+    /**
-    // only passed as `false` from FaintPhase (as opposed to other usages such
+     * Skip if the fainted party member has been revived already. doReturn is
-    // as ForceSwitchOutAttr or CheckSwitchPhase), so we only want to check this
+     * only passed as `false` from FaintPhase (as opposed to other usages such
-    // if the mon should have already been returned but is still alive and well
+     * as ForceSwitchOutAttr or CheckSwitchPhase), so we only want to check this
-    // on the field. see also; battle.test.ts
+     * if the mon should have already been returned but is still alive and well
+     * on the field. see also; battle.test.ts
+     */
     if (this.isModal && !this.doReturn && !this.scene.getParty()[this.fieldIndex].isFainted()) {
       return super.end();
     }
@@ -57,7 +63,8 @@ export class SwitchPhase extends BattlePhase {
 
     this.scene.ui.setMode(Mode.PARTY, this.isModal ? PartyUiMode.FAINT_SWITCH : PartyUiMode.POST_BATTLE_SWITCH, fieldIndex, (slotIndex: integer, option: PartyOption) => {
       if (slotIndex >= this.scene.currentBattle.getBattlerCount() && slotIndex < 6) {
-        this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, fieldIndex, slotIndex, this.doReturn, option === PartyOption.PASS_BATON));
+        const switchType = (option === PartyOption.PASS_BATON) ? SwitchType.BATON_PASS : this.switchType;
+        this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, switchType, fieldIndex, slotIndex, this.doReturn));
       }
       this.scene.ui.setMode(Mode.MESSAGE).then(() => super.end());
     }, PartyUiHandler.FilterNonFainted);

src/phases/switch-summon-phase.ts

@@ -12,29 +12,31 @@ import i18next from "i18next";
 import { PostSummonPhase } from "./post-summon-phase";
 import { SummonPhase } from "./summon-phase";
 import { SubstituteTag } from "#app/data/battler-tags";
+import { SwitchType } from "#app/enums/switch-type";
 
 export class SwitchSummonPhase extends SummonPhase {
+  private switchType: SwitchType;
   private slotIndex: integer;
   private doReturn: boolean;
-  private batonPass: boolean;
 
   private lastPokemon: Pokemon;
 
   /**
      * Constructor for creating a new SwitchSummonPhase
      * @param scene {@linkcode BattleScene} the scene the phase is associated with
+     * @param switchType the type of switch behavior
      * @param fieldIndex integer representing position on the battle field
      * @param slotIndex integer for the index of pokemon (in party of 6) to switch into
      * @param doReturn boolean whether to render "comeback" dialogue
      * @param batonPass boolean if the switch is from baton pass
      * @param player boolean if the switch is from the player
      */
-  constructor(scene: BattleScene, fieldIndex: integer, slotIndex: integer, doReturn: boolean, batonPass: boolean, player?: boolean) {
+  constructor(scene: BattleScene, switchType: SwitchType, fieldIndex: integer, slotIndex: integer, doReturn: boolean, player?: boolean) {
     super(scene, fieldIndex, player !== undefined ? player : true);
 
+    this.switchType = switchType;
     this.slotIndex = slotIndex;
     this.doReturn = doReturn;
-    this.batonPass = batonPass;
   }
 
   start(): void {
@@ -64,7 +66,7 @@ export class SwitchSummonPhase extends SummonPhase {
 
     const pokemon = this.getPokemon();
 
-    if (!this.batonPass) {
+    if (this.switchType === SwitchType.SWITCH) {
       (this.player ? this.scene.getEnemyField() : this.scene.getPlayerField()).forEach(enemyPokemon => enemyPokemon.removeTagsBySourceId(pokemon.id));
       const substitute = pokemon.getTag(SubstituteTag);
       if (substitute) {
@@ -94,7 +96,7 @@ export class SwitchSummonPhase extends SummonPhase {
       ease: "Sine.easeIn",
       scale: 0.5,
       onComplete: () => {
-        pokemon.leaveField(!this.batonPass, false);
+        pokemon.leaveField(this.switchType === SwitchType.SWITCH, false);
         this.scene.time.delayedCall(750, () => this.switchAndSummon());
       }
     });
@@ -105,7 +107,7 @@ export class SwitchSummonPhase extends SummonPhase {
     const switchedInPokemon = party[this.slotIndex];
     this.lastPokemon = this.getPokemon();
     applyPreSwitchOutAbAttrs(PreSwitchOutAbAttr, this.lastPokemon);
-    if (this.batonPass && switchedInPokemon) {
+    if (this.switchType === SwitchType.BATON_PASS && switchedInPokemon) {
       (this.player ? this.scene.getEnemyField() : this.scene.getPlayerField()).forEach(enemyPokemon => enemyPokemon.transferTagsBySourceId(this.lastPokemon.id, switchedInPokemon.id));
       if (!this.scene.findModifier(m => m instanceof SwitchEffectTransferModifier && (m as SwitchEffectTransferModifier).pokemonId === switchedInPokemon.id)) {
         const batonPassModifier = this.scene.findModifier(m => m instanceof SwitchEffectTransferModifier
@@ -130,7 +132,7 @@ export class SwitchSummonPhase extends SummonPhase {
          * If this switch is passing a Substitute, make the switched Pokemon match the returned Pokemon's state as it left.
          * Otherwise, clear any persisting tags on the returned Pokemon.
          */
-        if (this.batonPass) {
+        if (this.switchType === SwitchType.BATON_PASS || this.switchType === SwitchType.SHED_TAIL) {
           const substitute = this.lastPokemon.getTag(SubstituteTag);
           if (substitute) {
             switchedInPokemon.x += this.lastPokemon.getSubstituteOffset()[0];
@@ -174,8 +176,13 @@ export class SwitchSummonPhase extends SummonPhase {
       pokemon.battleSummonData.turnCount--;
     }
 
-    if (this.batonPass && pokemon) {
+    if (this.switchType === SwitchType.BATON_PASS && pokemon) {
       pokemon.transferSummon(this.lastPokemon);
+    } else if (this.switchType === SwitchType.SHED_TAIL && pokemon) {
+      const subTag = this.lastPokemon.getTag(SubstituteTag);
+      if (subTag) {
+        pokemon.summonData.tags.push(subTag);
+      }
     }
 
     this.lastPokemon?.resetSummonData();

src/phases/turn-init-phase.ts

@@ -32,7 +32,7 @@ export class TurnInitPhase extends FieldPhase {
           this.scene.unshiftPhase(new GameOverPhase(this.scene));
         } else if (allowedPokemon.length >= this.scene.currentBattle.getBattlerCount() || (this.scene.currentBattle.double && !allowedPokemon[0].isActive(true))) {
           // If there is at least one pokemon in the back that is legal to switch in, force a switch.
-          p.switchOut(false);
+          p.switchOut();
         } else {
           // If there are no pokemon in the back but we're not game overing, just hide the pokemon.
           // This should only happen in double battles.

src/phases/turn-start-phase.ts

@@ -19,6 +19,7 @@ import { TurnEndPhase } from "./turn-end-phase";
 import { WeatherEffectPhase } from "./weather-effect-phase";
 import { BattlerIndex } from "#app/battle";
 import { TrickRoomTag } from "#app/data/arena-tag";
+import { SwitchType } from "#app/enums/switch-type";
 
 export class TurnStartPhase extends FieldPhase {
   constructor(scene: BattleScene) {
@@ -179,7 +180,8 @@ export class TurnStartPhase extends FieldPhase {
         this.scene.unshiftPhase(new AttemptCapturePhase(this.scene, turnCommand.targets![0] % 2, turnCommand.cursor!));//TODO: is the bang correct here?
         break;
       case Command.POKEMON:
-        this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, pokemon.getFieldIndex(), turnCommand.cursor!, true, turnCommand.args![0] as boolean, pokemon.isPlayer()));//TODO: is the bang correct here?
+        const switchType = turnCommand.args![0] ? SwitchType.BATON_PASS : SwitchType.SWITCH; // TODO: is the bang correct here?
+        this.scene.unshiftPhase(new SwitchSummonPhase(this.scene, switchType, pokemon.getFieldIndex(), turnCommand.cursor!, true, pokemon.isPlayer()));
         break;
       case Command.RUN:
         let runningPokemon = pokemon;

src/test/abilities/zen_mode.test.ts

@@ -18,6 +18,7 @@ import GameManager from "#test/utils/gameManager";
 import Phaser from "phaser";
 import { afterEach, beforeAll, beforeEach, describe, expect, test } from "vitest";
 import { Status, StatusEffect } from "#app/data/status-effect";
+import { SwitchType } from "#app/enums/switch-type";
 
 
 
@@ -113,7 +114,7 @@ describe("Abilities - ZEN MODE", () => {
       await game.phaseInterceptor.run(EnemyCommandPhase);
       await game.phaseInterceptor.run(TurnStartPhase);
       game.onNextPrompt("SwitchPhase", Mode.PARTY, () => {
-        game.scene.unshiftPhase(new SwitchSummonPhase(game.scene, 0, 1, false, false));
+        game.scene.unshiftPhase(new SwitchSummonPhase(game.scene, SwitchType.SWITCH, 0, 1, false));
         game.scene.ui.setMode(Mode.MESSAGE);
       });
       game.onNextPrompt("SwitchPhase", Mode.MESSAGE, () => {

src/test/moves/shed_tail.test.ts

@@ -0,0 +1,56 @@
+import { SubstituteTag } from "#app/data/battler-tags";
+import { Abilities } from "#enums/abilities";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import GameManager from "#test/utils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, it, expect } from "vitest";
+
+describe("Moves - Shed Tail", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+    game.override
+      .moveset([Moves.SHED_TAIL])
+      .battleType("single")
+      .enemySpecies(Species.SNORLAX)
+      .enemyAbility(Abilities.BALL_FETCH)
+      .enemyMoveset(Moves.SPLASH);
+  });
+
+  it("transfers a Substitute doll to the switched in Pokemon", async () => {
+    await game.classicMode.startBattle([Species.MAGIKARP, Species.FEEBAS]);
+
+    const magikarp = game.scene.getPlayerPokemon()!;
+
+    game.move.select(Moves.SHED_TAIL);
+    game.doSelectPartyPokemon(1);
+
+    await game.phaseInterceptor.to("TurnEndPhase", false);
+
+    const feebas = game.scene.getPlayerPokemon()!;
+    const substituteTag = feebas.getTag(SubstituteTag);
+
+    expect(feebas).not.toBe(magikarp);
+    expect(feebas.hp).toBe(feebas.getMaxHp());
+    // Note: Shed Tail's HP cost is currently not accurate to mainline, as it
+    // should cost ceil(maxHP / 2) instead of max(floor(maxHp / 2), 1). The current
+    // implementation is consistent with Substitute's HP cost logic, but that's not
+    // the case in mainline for some reason :regiDespair:.
+    expect(magikarp.hp).toBe(Math.ceil(magikarp.getMaxHp() / 2));
+    expect(substituteTag).toBeDefined();
+    expect(substituteTag?.hp).toBe(Math.floor(magikarp.getMaxHp() / 4));
+  });
+});