Giratina

Choose 1 of your opponent's Benched Pokémon. This attack does 20 damage to that Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.) Flip a coin. If heads, prevent all effects of an attack, including damage, done to Giratina during your opponent's next turn.

Does 50 damage plus 10 more damage for each damage counter on the Defending Pokémon.