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

Holon Blizzard

20

If Snow-cloud Castform has any Holon Energy cards attached to it, this attack does 10 damage to each of your opponent's Benched Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.)