Fix boss faint dialogue showing on party member faint

src/battle-phases.ts

@@ -2554,12 +2554,14 @@ export class FaintPhase extends PokemonPhase {
   tryOverrideForBattleSpec(): boolean {
     switch (this.scene.currentBattle.battleSpec) {
       case BattleSpec.FINAL_BOSS:
+        if (!this.player) {
           const enemy = this.getPokemon();
           if (enemy.formIndex) {
             this.scene.ui.showDialogue(battleSpecDialogue[BattleSpec.FINAL_BOSS].secondStageWin, enemy.name, null, () => this.doFaint(), null, true);
             return true;
           }
         }
+    }
 
     return false;
   }