You can't have more than 1 ACE SPEC card in your deck.
Play Clefairy Doll as if it were a Basic Pokémon. While in play, Clefairy Doll counts as a Pokémon (instead of a Trainer card). Clefairy Doll has no attacks, can't retreat, and can't be Asleep, Confused, Paralyzed, or Poisoned. If Clefairy Doll is Knocked Out, it doesn't count as a Knocked Out Pokémon. At any time during your turn before your attack, you may discard Clefairy Doll.