When a Pokemon is Asleep, it can't use any moves nor open the menu. Held items also can't be removed from the sleeping Pokemon. It lasts 3 to 6 turns. A Pokemon with the Sleepless status condition can't fall asleep, and Pokemon with the Early Bird ability has the number of turns halved.
It could be caused by the moves Sleep Powder, Hypnosis , Spore, Sing, Secret Power and Lovely Kiss.
It can be caused by the items Slumber Orb, Grimy Food and Sleep Seed.
The Ability Effect Spore may also cause the Asleep status ailment.
'The Pokemon falls asleep and becomes
incapable of any action.
Its effects lasts a set amount of turns.'