A Water Type Pokemon carried around by the Water Gym Leader Misty.
Staryu is the main Water Pokemon used by Misty in the Pokemon series. Even though the Pokemon's appearence has been scattered throughout the series, the time when most appearences was made were in the first couple of seasons, when Misty was with Ash. We occasionally see Straryu throughout the rest of Ash's and the other Pokemon Trainers journey. Staryu has been given a place in each poikemon game so far, and are being used in the future is the communities guess.
Staryu first appeared in the anime series in Pokemon: Episode # 7. It is first used by Gym leader Misty in the gym battle against Ash.