Gengar

Once during your turn (before your attack), you may move 1 damage counter from 1 of your opponent's Pokémon to another of your opponent's Pokémon. This power can't be used if Gengar is affected by a Special Condition.

Does 10 damage to 1 of your opponent's Benched Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.) You may switch Gengar with 1 of your Benched Pokémon.