Effect Spore

Introduced in Generation III

Whenever a move makes contact with this Pokémon, the move's user has a 30% chance of being paralyzed, poisoned, or put to sleep, chosen at random. Nothing is done to compensate if the move's user is immune to one of these ailments; there is simply a lower chance that the move's user will be affected.

“Contact with the Pokémon may inflict poison, sleep, or paralysis on the attacker.”