Effect Spore is an ability that causes attacking enemy Pokémon in close proximity to be inflicted with a status condition.
If a Pokémon with Effect Spore is attacked and is within 1 tile of the attacker, there is a 1 in 4 chance for the attacker to be inflicted with a status condition. Both physical and special attacks can trigger the ability.
There are three status conditions that can be inflicted: Poison, Paralysis, and Sleep.
Pokémon with Effect Spore