Ultra-sun: They’re popular, but they’re rare. Trainers who show them off recklessly may be targeted by thieves.Moon: On nights with a full moon, they gather together and dance. The surrounding area is enveloped in an abnormal magnetic field.Alpha-sapphire: On every night of a full moon, groups of this Pokémon come out to play. When dawn arrives, the tired Clefairy return to their quiet mountain retreats and go to sleep nestled up against each other.
Prof. Lotus' Notes: Clefairy is unofically referred to as an Extraterrestrial Pokémon and are said to come to earth on meteorites as Cleffa.