Clefairy is a bipedal, pink Pokémon with a chubby, vaguely star-shaped body. A small, pointed tooth protrudes from the upper left corner of its mouth. It has wrinkles beside its black, oval eyes, dark pink, oval markings on its cheeks, two small wings, and large, pointed ears with brown tips. A tuft of fur curls over its forehead, much like its large, upward-curling tail. Each stocky arm has two small claws and a thumb on each hand, and each of its feet has a single toenail.
Clefairy is very shy and rarely shows itself to humans. On the rare occasions it does come down from its mountain home, it can be seen dancing under the light of the full moon. Once the sun starts to rise, it returns home where it sleeps nestled with other Clefairy. Though incapable of flight, Clefairy's wings can store moonlight and allow it to float. The anime has shown that Clefairy is actually an extraterrestrial Pokémon.
The second chapter to feature Clefairy is Clefairy in Space, the tenth chapter of the manga. In this chapter, a herd of wild Clefairy are causing trouble in Apple City, where rumors are circulating that Clefairy come from outer space. This chapter was based on the anime episode Clefairy Tales. In this chapter, it is learned that Clefairy have a secretion from the back of their throat that can harden into a crystal-like form.
One of Hazel's main traveling companions in the Magical Pokémon Journey manga is a timid, shy Clefairy. Clefairy tends to be very cowardly, but when he actually does battle, he can use his powerful Metronome attack.
Clefairy also uses Metronome but uses its own series of attacks such as Blizzard, Explosion, or Fire Spin. All will hurt any opponents close to Clefairy.
Clefairy are very cute Pokémon, which makes them popular pets. However, as they're only found in a few areas, it takes a lot of work to find one. Strangely enough, legend has it that Clefairy are more active during the full moon. These Pokémon are known to use Metronome, a move that unleashes a randomly selected technique.
Pokémon Stadium: Clefairy stars in the mini-game "Clefairy Says." Players are given a pattern of arrows to repeat back. Each time the player messes up, they will receive a strike. After five strikes, the player is out. The last Clefairy standing wins.
Clefairy was originally going to be the official mascot of Pokémon, but Pikachu was used instead due to the popularity of the anime and Pikachu's familiarity with fans.
In the original pilot episode of the anime, Clefairy was intended to be Ash's starting Pokémon. Due to a last minute change, the role went to Pikachu. This would have made the anime closer to the Pokémon Pocket Monsters manga, which would later be referenced in Lights, Camerupt, Action!, where its main character, Red, along with his Clefairy starred in a film that Ash and Gary were watching when they were younger.