implement Costar ability, refactor TraceAbAttr to be more generic

src/data/ability.ts

@@ -1391,7 +1391,20 @@ export class PostIntimidateStatChangeAbAttr extends AbAttr {
   }
 }
 
+/** 
+ * Base class for defining all {@linkcode Ability} Attributes post summon 
+ * @abstract
+ * @see {@linkcode applyPostSummon()}
+ */
 export class PostSummonAbAttr extends AbAttr {
+  /**
+   * Applies ability post summon (after switching in)
+   * @abstract
+   * @param pokemon {@linkcode Pokemon} with this ability
+   * @param passive Whether this ability is a passive
+   * @param args Set of unique arguments needed by this attribute
+   * @returns true if application of the ability succeeds
+   */
   applyPostSummon(pokemon: Pokemon, passive: boolean, args: any[]): boolean | Promise<boolean> {
     return false;
   }
@@ -1612,8 +1625,57 @@ export class PostSummonFormChangeAbAttr extends PostSummonAbAttr {
   }
 }
 
-export class TraceAbAttr extends PostSummonAbAttr {
+/** Attempts to copy `copyTarget` after entering the battle  */
+export class PostSummonCopyAbAttr extends PostSummonAbAttr {
+  /**
+   * @param copyTarget what to attempt to copy
+   * @param test this is a test
+   */
+  constructor(
+    private copyTarget: "OPP_ABILITY" | "ALLY_STAT_CHANGES", /** Extend this to add more options */
+  ) {
+    super()
+  }
+
   applyPostSummon(pokemon: Pokemon, passive: boolean, args: any[]): boolean {
+    switch (this.copyTarget) {
+      case "OPP_ABILITY":
+        return this.copyAbility(pokemon)
+      case "ALLY_STAT_CHANGES":
+        return this.copyAllyStatChanges(pokemon)
+      default:
+        return false
+    }
+  }
+
+  /**
+   * Copy the stat changes on an ally pokemon
+   * @param pokemon - that will receive the stat changes
+   * @returns true if successful
+   */
+  copyAllyStatChanges(pokemon: Pokemon): boolean {
+    if (!pokemon.scene.currentBattle.double) {
+      return false
+    }
+
+    const ally = pokemon.getAlly()
+    if (!ally || !ally.summonData.battleStats.some(change => change > 0)) {
+      return false
+    }
+
+    pokemon.summonData.battleStats = ally.summonData.battleStats
+    pokemon.updateInfo()
+    pokemon.scene.queueMessage(getPokemonMessage(pokemon, ` copied ${ally.name}'s stat changes!`))
+
+    return true
+  }
+
+  /**
+   * Copy the ability of an enemy pokemon post summon
+   * @param pokemon - that will receive the ability
+   * @returns true if successful
+   */
+  copyAbility(pokemon: Pokemon): boolean {
     const targets = pokemon.getOpponents();
     if (!targets.length)
       return false;
@@ -1624,12 +1686,16 @@ export class TraceAbAttr extends PostSummonAbAttr {
     else
       target = targets[0];
 
-    // Wonder Guard is normally uncopiable so has the attribute, but trace specifically can copy it
+    if (
-    if (target.getAbility().hasAttr(UncopiableAbilityAbAttr) && target.getAbility().id !== Abilities.WONDER_GUARD)
+      target.getAbility().hasAttr(UncopiableAbilityAbAttr) && 
-      return false;
+      // Wonder Guard is normally uncopiable so has the attribute, but trace specifically can copy it
+      !(pokemon.hasAbility(Abilities.TRACE) && target.getAbility().id === Abilities.WONDER_GUARD)
+    ) {
+      return false
+    }
 
     pokemon.summonData.ability = target.getAbility().id;
-
+    pokemon.updateInfo()
     pokemon.scene.queueMessage(getPokemonMessage(pokemon, ` traced ${target.name}'s\n${allAbilities[target.getAbility().id].name}!`));
 
     return true;
@@ -3107,7 +3173,7 @@ export function initAbilities() {
       .attr(DoubleBattleChanceAbAttr)
       .ignorable(),
     new Ability(Abilities.TRACE, 3)
-      .attr(TraceAbAttr)
+      .attr(PostSummonCopyAbAttr, "OPP_ABILITY")
       .attr(UncopiableAbilityAbAttr),
     new Ability(Abilities.HUGE_POWER, 3)
       .attr(BattleStatMultiplierAbAttr, BattleStat.ATK, 2),
@@ -3901,6 +3967,7 @@ export function initAbilities() {
     new Ability(Abilities.SUPREME_OVERLORD, 9)
       .unimplemented(),
     new Ability(Abilities.COSTAR, 9)
+      .attr(PostSummonCopyAbAttr, "ALLY_STAT_CHANGES")
       .unimplemented(),
     new Ability(Abilities.TOXIC_DEBRIS, 9)
       .attr(PostDefendApplyArenaTrapTagAbAttr, (target, user, move) => move.category === MoveCategory.PHYSICAL, ArenaTagType.TOXIC_SPIKES)