Goldeen is a Water pokemon introduced in Generation I. It evolves into Seaking at level 33.
Goldeen joined TDWT/TM in Episode 19. She was a compulsive liar, which made her unpopular with the cast, but at the same time she wasn't a threat so she wasn't a target. She later evolved into Seaking.
Goldeen is the Harold of the cast, so he has a crush on Kirlia but got tangeled into in an alliance with Yanmega, who he grows to not trust. Goldeen proves to be an effective addition to Team Mawile, winning the chess challenge and in Episode 13, with some intense training, Goldeen evolves into Seaking.