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.[1][2]
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.
