Misty's Azurill is a Pokémon that Misty caught in Kanto. It still resides with her in the Cerulean Gym.
Misty's Azurill was the offspring of Tracey's Marill, and he gave it to Misty when she was very young. However, it has only been seen on two occasions, appearing only in the episodes The Right Place and the Right Mime, as well as A Real Cleffa-Hanger. In both these episodes, Misty was seen carrying Marill, and only battles Team Rocket in the latter episode.
Water Gun (First used in The Right Place and the Right Mime)