Rocket's Sneasel ex

Before doing damage, you may switch 1 of your opponent's Benched Pokémon with the Defending Pokémon. If you do, this attack does 10 damage to the new Defending Pokémon. Your opponent chooses the Defending Pokémon to switch.

Does 30 damage plus 10 more damage for each of your Darkness Pokémon in play."

Ryo Ueda