As long as this Pokémon is in the Active Spot, your opponent can't have more than 3 Benched Pokémon. If they have 4 or more Benched Pokémon, they discard Benched Pokémon until they have 3 Pokémon on the Bench. If more than one effect changes the number of Benched Pokémon allowed, use the smaller number.

Your opponent's Active Pokémon is now Poisoned.

Pokémon ex rule: When your Pokémon ex is Knocked Out, your opponent takes 2 Prize cards.