Ability: Dust Field

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.