Walrein

Once during your turn, when you play Walrein from your hand to evolve 1 of your Pokémon, you may flip 2 coins. If both are heads, discard 1 of the Defending Pokémon and all cards attached to it. (This doesn't count as a Knocked Out Pokémon.)

If your opponent doesn't discard a card from his or her hand, the Defending Pokémon is now Paralyzed.