Implement proof of concept of Friend Guard ability

src/data/ability.ts

@@ -2690,6 +2690,18 @@ export class IgnoreTypeStatusEffectImmunityAbAttr extends AbAttr {
   }
 }
 
+export class FriendGuardAbAttr extends AbAttr {
+  apply(pokemon: Pokemon, passive: boolean, cancelled: Utils.BooleanHolder, args: any[]): boolean {
+    const ally = pokemon.getAlly();
+    if (!ally) {
+      return false;
+    }
+    ally.addTag(BattlerTagType.FRIEND_GUARD, 1, undefined, pokemon.id);
+
+    return true;
+  }
+}
+
 function applyAbAttrsInternal<TAttr extends AbAttr>(attrType: { new(...args: any[]): TAttr },
   pokemon: Pokemon, applyFunc: AbAttrApplyFunc<TAttr>, args: any[], isAsync: boolean = false, showAbilityInstant: boolean = false, quiet: boolean = false, passive: boolean = false): Promise<void> {
   return new Promise(resolve => {
@@ -3263,8 +3275,8 @@ export function initAbilities() {
     new Ability(Abilities.HEALER, 5)
       .conditionalAttr(pokemon => pokemon.getAlly() && Utils.randSeedInt(10) < 3, PostTurnResetStatusAbAttr, true),
     new Ability(Abilities.FRIEND_GUARD, 5)
-      .ignorable()
+      .attr(FriendGuardAbAttr)
-      .unimplemented(),
+      .ignorable(),
     new Ability(Abilities.WEAK_ARMOR, 5)
       .attr(PostDefendStatChangeAbAttr, (target, user, move) => move.category === MoveCategory.PHYSICAL, BattleStat.DEF, -1)
       .attr(PostDefendStatChangeAbAttr, (target, user, move) => move.category === MoveCategory.PHYSICAL, BattleStat.SPD, 2),

src/data/battler-tags.ts

@@ -1249,6 +1249,24 @@ export class CursedTag extends BattlerTag {
   }
 }
 
+export class FriendGuardTag extends BattlerTag {
+  public powerMultiplier: number;
+
+  constructor(powerMultiplier: number) {
+    super(BattlerTagType.FRIEND_GUARD, BattlerTagLapseType.PRE_MOVE, 1, undefined);
+    this.powerMultiplier = 1 - powerMultiplier;
+  }
+
+  /**
+  * When given a battler tag or json representing one, load the data for it.
+  * @param {BattlerTag | any} source A battler tag
+  */
+  loadTag(source: BattlerTag | any): void {
+    super.loadTag(source);
+    this.powerMultiplier = source.powerMultiplier;
+  }
+}
+
 export function getBattlerTag(tagType: BattlerTagType, turnCount: integer, sourceMove: Moves, sourceId: integer): BattlerTag {
   switch (tagType) {
     case BattlerTagType.RECHARGING:
@@ -1358,6 +1376,8 @@ export function getBattlerTag(tagType: BattlerTagType, turnCount: integer, sourc
       return new TypeBoostTag(tagType, sourceMove, Type.ELECTRIC, 2, true);
     case BattlerTagType.MAGNET_RISEN:
       return new MagnetRisenTag(tagType, sourceMove);
+    case BattlerTagType.FRIEND_GUARD:
+      return new FriendGuardTag(0.25);
     case BattlerTagType.NONE:
     default:
         return new BattlerTag(tagType, BattlerTagLapseType.CUSTOM, turnCount, sourceMove, sourceId);

src/data/enums/battler-tag-type.ts

@@ -55,5 +55,6 @@ export enum BattlerTagType {
   CURSED = "CURSED",
   CHARGED = "CHARGED",
   GROUNDED = "GROUNDED",
-  MAGNET_RISEN = "MAGNET_RISEN"
+  MAGNET_RISEN = "MAGNET_RISEN",
+  FRIEND_GUARD = "FRIEND_GUARD"
 }

src/field/pokemon.ts

@@ -19,7 +19,7 @@ import { pokemonEvolutions, pokemonPrevolutions, SpeciesFormEvolution, SpeciesEv
 import { reverseCompatibleTms, tmSpecies, tmPoolTiers } from '../data/tms';
 import { DamagePhase, FaintPhase, LearnMovePhase, ObtainStatusEffectPhase, StatChangePhase, SwitchSummonPhase } from '../phases';
 import { BattleStat } from '../data/battle-stat';
-import { BattlerTag, BattlerTagLapseType, EncoreTag, HelpingHandTag, HighestStatBoostTag, TypeBoostTag, getBattlerTag } from '../data/battler-tags';
+import { BattlerTag, BattlerTagLapseType, EncoreTag, FriendGuardTag, HelpingHandTag, HighestStatBoostTag, TypeBoostTag, getBattlerTag } from '../data/battler-tags';
 import { BattlerTagType } from "../data/enums/battler-tag-type";
 import { Species } from '../data/enums/species';
 import { WeatherType } from '../data/weather';
@@ -1448,6 +1448,14 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
         this.scene.getField(true).map(p => applyPreAttackAbAttrs(FieldVariableMovePowerAbAttr, this, source, battlerMove, power));
 
         applyPreDefendAbAttrs(ReceivedMoveDamageMultiplierAbAttr, this, source, battlerMove, cancelled, power);
+        const reducedDamageTag = this.getTag(BattlerTagType.FRIEND_GUARD) as FriendGuardTag;
+        console.log(this.findTags(t => true));
+        if (reducedDamageTag) {
+          console.log(power);
+          console.log(reducedDamageTag.powerMultiplier);
+          power.value *= reducedDamageTag.powerMultiplier;
+          console.log(power);
+        }
 
         power.value *= typeChangeMovePowerMultiplier.value;
 

src/phases.ts

@@ -30,7 +30,7 @@ import { Weather, WeatherType, getRandomWeatherType, getTerrainBlockMessage, get
 import { TempBattleStat } from "./data/temp-battle-stat";
 import { ArenaTagSide, ArenaTrapTag, MistTag, TrickRoomTag } from "./data/arena-tag";
 import { ArenaTagType } from "./data/enums/arena-tag-type";
-import { CheckTrappedAbAttr, IgnoreOpponentStatChangesAbAttr, PostAttackAbAttr, PostBattleAbAttr, PostDefendAbAttr, PostSummonAbAttr, PostTurnAbAttr, PostWeatherLapseAbAttr, PreSwitchOutAbAttr, PreWeatherDamageAbAttr, ProtectStatAbAttr, RedirectMoveAbAttr, BlockRedirectAbAttr, RunSuccessAbAttr, StatChangeMultiplierAbAttr, SuppressWeatherEffectAbAttr, SyncEncounterNatureAbAttr, applyAbAttrs, applyCheckTrappedAbAttrs, applyPostAttackAbAttrs, applyPostBattleAbAttrs, applyPostDefendAbAttrs, applyPostSummonAbAttrs, applyPostTurnAbAttrs, applyPostWeatherLapseAbAttrs, applyPreStatChangeAbAttrs, applyPreSwitchOutAbAttrs, applyPreWeatherEffectAbAttrs, BattleStatMultiplierAbAttr, applyBattleStatMultiplierAbAttrs, IncrementMovePriorityAbAttr, applyPostVictoryAbAttrs, PostVictoryAbAttr, applyPostBattleInitAbAttrs, PostBattleInitAbAttr, BlockNonDirectDamageAbAttr as BlockNonDirectDamageAbAttr, applyPostKnockOutAbAttrs, PostKnockOutAbAttr, PostBiomeChangeAbAttr, applyPostFaintAbAttrs, PostFaintAbAttr, IncreasePpAbAttr, PostStatChangeAbAttr, applyPostStatChangeAbAttrs, AlwaysHitAbAttr, PreventBerryUseAbAttr, StatChangeCopyAbAttr } from "./data/ability";
+import { CheckTrappedAbAttr, IgnoreOpponentStatChangesAbAttr, PostAttackAbAttr, PostBattleAbAttr, PostDefendAbAttr, PostSummonAbAttr, PostTurnAbAttr, PostWeatherLapseAbAttr, PreSwitchOutAbAttr, PreWeatherDamageAbAttr, ProtectStatAbAttr, RedirectMoveAbAttr, BlockRedirectAbAttr, RunSuccessAbAttr, StatChangeMultiplierAbAttr, SuppressWeatherEffectAbAttr, SyncEncounterNatureAbAttr, applyAbAttrs, applyCheckTrappedAbAttrs, applyPostAttackAbAttrs, applyPostBattleAbAttrs, applyPostDefendAbAttrs, applyPostSummonAbAttrs, applyPostTurnAbAttrs, applyPostWeatherLapseAbAttrs, applyPreStatChangeAbAttrs, applyPreSwitchOutAbAttrs, applyPreWeatherEffectAbAttrs, BattleStatMultiplierAbAttr, applyBattleStatMultiplierAbAttrs, IncrementMovePriorityAbAttr, applyPostVictoryAbAttrs, PostVictoryAbAttr, applyPostBattleInitAbAttrs, PostBattleInitAbAttr, BlockNonDirectDamageAbAttr as BlockNonDirectDamageAbAttr, applyPostKnockOutAbAttrs, PostKnockOutAbAttr, PostBiomeChangeAbAttr, applyPostFaintAbAttrs, PostFaintAbAttr, IncreasePpAbAttr, PostStatChangeAbAttr, applyPostStatChangeAbAttrs, AlwaysHitAbAttr, PreventBerryUseAbAttr, StatChangeCopyAbAttr, FriendGuardAbAttr } from "./data/ability";
 import { Unlockables, getUnlockableName } from "./system/unlockables";
 import { getBiomeKey } from "./field/arena";
 import { BattleType, BattlerIndex, TurnCommand } from "./battle";
@@ -1616,6 +1616,7 @@ export class TurnInitPhase extends FieldPhase {
 
     this.scene.getField().forEach((pokemon, i) => {
       if (pokemon?.isActive()) {
+        applyAbAttrs(FriendGuardAbAttr, pokemon, undefined);
         if (pokemon.isPlayer())
           this.scene.currentBattle.addParticipant(pokemon as PlayerPokemon);