Glimmora ex - 218/091 - SV: Paldean Fates (PAF)

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 Pokemon until they have 3 Pokemon on the Bench. If more than one effect changes the number of Benched Pokémon allowed, use the smaller number:

[FF] Poisonous Gem (140)
Your opponent's Active Pokémon is now Poisoned.