Implement Transform move and Imposter ability

src/data/ability.ts

@@ -9,6 +9,7 @@ import { BattlerTag, BattlerTagType } from "./battler-tag";
 import { StatusEffect, getStatusEffectDescriptor } from "./status-effect";
 import { MoveFlags, Moves, RecoilAttr } from "./move";
 import { ArenaTagType } from "./arena-tag";
+import { Stat } from "./pokemon-stat";
 
 export class Ability {
   public id: Abilities;
@@ -487,6 +488,35 @@ export class PostSummonWeatherChangeAbAttr extends PostSummonAbAttr {
   }
 }
 
+export class PostSummonTransformAbAttr extends PostSummonAbAttr {
+  constructor() {
+    super(true);
+  }
+
+  applyPostSummon(pokemon: Pokemon, args: any[]): boolean {
+    const targets = pokemon.getOpponents();
+    let target: Pokemon;
+    if (targets.length > 1)
+      pokemon.scene.executeWithSeedOffset(() => target = Phaser.Math.RND.pick(targets), pokemon.scene.currentBattle.waveIndex);
+    else
+      target = targets[0];
+
+    pokemon.summonData.speciesForm = target.getSpeciesForm();
+    pokemon.summonData.gender = target.getGender();
+    pokemon.summonData.stats = [ pokemon.stats[Stat.HP] ].concat(target.stats.slice(1));
+    pokemon.summonData.battleStats = target.summonData.battleStats.slice(0);
+    pokemon.summonData.moveset = target.getMoveset().map(m => new PokemonMove(m.moveId, m.ppUsed, m.ppUp));
+    pokemon.summonData.types = target.getTypes();
+    
+    pokemon.scene.playSound('PRSFX- Transform');
+    pokemon.loadAssets().then(() => pokemon.playAnim());
+
+    pokemon.scene.queueMessage(getPokemonMessage(pokemon, ` transformed\ninto ${target.name}!`));
+
+    return true;
+  }
+}
+
 export class PreStatChangeAbAttr extends AbAttr {
   applyPreStatChange(pokemon: Pokemon, stat: BattleStat, cancelled: Utils.BooleanHolder, args: any[]): boolean {
     return false;
@@ -1437,7 +1467,8 @@ export function initAbilities() {
     new Ability(Abilities.HEALER, "Healer (N)", "May heal an ally's status conditions.", 5),
     new Ability(Abilities.HEAVY_METAL, "Heavy Metal (N)", "Doubles the Pokémon's weight.", 5),
     new Ability(Abilities.ILLUSION, "Illusion (N)", "Enters battle disguised as the last Pokémon in the party.", 5),
-    new Ability(Abilities.IMPOSTER, "Imposter (N)", "It transforms itself into the Pokémon it is facing.", 5),
+    new Ability(Abilities.IMPOSTER, "Imposter", "It transforms itself into the Pokémon it is facing.", 5)
+      .attr(PostSummonTransformAbAttr),
     new Ability(Abilities.INFILTRATOR, "Infiltrator (N)", "Passes through the foe's barrier and strikes.", 5),
     new Ability(Abilities.IRON_BARBS, "Iron Barbs (N)", "Inflicts damage to the Pokémon on contact.", 5),
     new Ability(Abilities.JUSTIFIED, "Justified (N)", "Raises Attack when hit by a Dark-type move.", 5),

src/data/move.ts

@@ -2199,6 +2199,29 @@ export class SketchAttr extends MoveEffectAttr {
   }
 }
 
+export class TransformAttr extends MoveEffectAttr {
+  apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): Promise<boolean> {
+    return new Promise(resolve => {
+      if (!super.apply(user, target, move, args))
+        return resolve(false);
+
+      user.summonData.speciesForm = target.getSpeciesForm();
+      user.summonData.gender = target.getGender();
+      user.summonData.stats = [ user.stats[Stat.HP] ].concat(target.stats.slice(1));
+      user.summonData.battleStats = target.summonData.battleStats.slice(0);
+      user.summonData.moveset = target.getMoveset().map(m => new PokemonMove(m.moveId, m.ppUsed, m.ppUp));
+      user.summonData.types = target.getTypes();
+
+      user.scene.queueMessage(getPokemonMessage(user, ` transformed\ninto ${target.name}!`));
+      
+      user.loadAssets().then(() => {
+        user.playAnim();
+        resolve(true);
+      });
+    });
+  }
+}
+
 const failOnGravityCondition = (user: Pokemon, target: Pokemon, move: Move) => !user.scene.arena.getTag(ArenaTagType.GRAVITY);
 
 export type MoveAttrFilter = (attr: MoveAttr) => boolean;
@@ -2611,7 +2634,8 @@ export function initMoves() {
       .makesContact(false)
       .ignoresVirtual()
       .target(MoveTarget.OTHER),
-    new SelfStatusMove(Moves.TRANSFORM, "Transform (N)", Type.NORMAL, -1, 10, -1, "User takes on the form and attacks of the opponent.", -1, 0, 1),
+    new StatusMove(Moves.TRANSFORM, "Transform", Type.NORMAL, -1, 10, -1, "User takes on the form and attacks of the opponent.", -1, 0, 1)
+      .attr(TransformAttr),
     new AttackMove(Moves.BUBBLE, "Bubble", Type.WATER, MoveCategory.SPECIAL, 40, 100, 30, -1, "May lower opponent's Speed.", 10, 0, 1)
       .attr(StatChangeAttr, BattleStat.SPD, -1)
       .target(MoveTarget.ALL_NEAR_ENEMIES),