Collapsed Stadium (Brilliant Stars 137/172)

Rules

Each player can't have more than 4 Benched Pokémon. If a player has 5 or more Benched Pokémon, they discard Benched Pokémon until they have 4 Pokémon on the Bench. The player who played this card discards first. If more than one effect changes the number of Benched Pokémon allowed, use the smaller number.