Castform

Poké-Power Temperamental Weather

Once during your turn (before your attack), you may search your deck for Sunny Castform, Rain Castform, or Snow-cloud Castform and switch it with Castform. (Any cards attached to Castform, damage counters, Special Conditions, and effects on it are now on the new Pokémon.) Shuffle Castform back into your deck. You can't use more than 1 Temperamental Weather Poké-Power each turn.