Golem

Whenever you attach a Grass, Fire, or Fighting basic Energy card from your hand to Golem, Golem's type (color) becomes the same as that type of Energy until the end of the turn.

Golem does 20 damage to itself. This attack also does 10 damage to each Benched Pokémon (yours and your opponent's). (Don't apply Weakness and Resistance for Benched Pokémon.)