Ditto

Pokémon Power: Amazing Transformation Once during your turn (before your attack), if this Pokémon is your Active Pokémon, you may flip a coin. If heads, choose any Pokémon in play. From now on treat this Pokémon as if it were the same card as that Pokémon, including Hit Points, Weakness, and so on, except this Pokémon can't evolve or devolve, always can use this Pokémon Power, and you may treat any Energy attached to Ditto as Energy of any type. If tails; if this Pokémon is Benched; if this Pokémon becomes Asleep, Confused, or Paralyzed; or if the Pokémon you chose leaves play, treat this card as this Pokémon again. This power can't be used if this Pokémon is Asleep, Confused, or Paralyzed.