Hitmontop #37

Flip a coin until you get tails. This attack does 20 damage times the number of heads.

If your opponent has any Benched Pokémon, he or she chooses 1 of them and switches it with his or her Active Pokémon, then, if you have any Benched Pokémon, you switch 1 of them with your Active Pokémon. (Do the damage before switching the Pokémon.)