UPNetwork -> Anime -> Kanto -> The Misty Mermaid
#61 "The Misty Mermaid"
Misty's Horsea is tired and needs a big place to swim, so Team Ash head to Cerulean. When they get there, they find that Misty's sisters have organised a big water show - with HER as the star! Their performances aren't bringing in the crowds any more, so they wanted to showcase 'new talent'. Misty reluctantly agrees and plays the part of a mermaid, with lots of water Pokémon as her friends. Team Rocket appears and continues in the water ballet, although they were not part of the performance (all the spectators think they are). They want to steal the water Pokémon.
Misty fights back with the water Pokémon, who are soundly beaten - ALL of them, even though they belong to gym leaders! - just by Jessie's Arbok. But then, the Cerulean Gym's Seel evolves into Dewgong, and Misty beats Team Rocket with powerful ice attacks. The show finishes, and the audience thinks it was great. Afterwards, Misty's sisters force Misty to leave her Horsea and Starmie (?!) with them so they can have more Pokémon for their future water shows. -_-;