src/data/abilities/ability.ts

@@ -3903,7 +3903,12 @@ export class PostSummonTransformAbAttr extends PostSummonAbAttr {
     const targets = pokemon.getOpponents();
     const target = this.getTarget(targets);
 
-    if (target?.summonData?.illusion || pokemon?.isTransformed() || target?.isTransformed()) {
+    //Prevents Imposter from triggering on a transformed target or if the user is already transformed
+    if (pokemon?.isTransformed() || target?.isTransformed()) {
+      return false;
+    }
+
+    if (target?.summonData?.illusion) {
       return false;
     }
 

src/data/moves/move.ts

@@ -7610,13 +7610,13 @@ export class SuppressAbilitiesIfActedAttr extends MoveEffectAttr {
  */
 export class TransformAttr extends MoveEffectAttr {
   override apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
-    if (!super.apply(user, target, move, args) || (target.isTransformed() || user.isTransformed())) {
+    if (!super.apply(user, target, move, args)) {
-      globalScene.phaseManager.queueMessage(i18next.t("battle:attackFailed"));
       return false;
     }
 
     globalScene.phaseManager.unshiftNew("PokemonTransformPhase", user.getBattlerIndex(), target.getBattlerIndex());
 
+
     return true;
   }
 }

src/phases/move-phase.ts

@@ -339,6 +339,17 @@ export class MovePhase extends BattlePhase {
       this.showMoveText();
     }
 
+    if (
+      //Prevent using Transform if either the user or target is already transformed
+      this.move.getMove().id === MoveId.TRANSFORM &&
+      (targets[0].isTransformed() || this.pokemon.isTransformed())
+    ) {
+      this.showMoveText();
+      this.showFailedText();
+      this.end();
+      return;
+    }
+
     // Clear out any two turn moves once they've been used.
     // TODO: Refactor move queues and remove this assignment;
     // Move queues should be handled by the calling `CommandPhase` or a manager for it