It was not used nearly as often as her Staryu and is implied to be weaker in battle, despite being Staryu's evolved form. Starmie is used more for transport than for battle, often carrying Misty across water, although it is unknown if it is capable of actually using Surf (in the anime, a Pokémon does not need to know Surf in order to carry their trainer across water).
In The Water Flowers of Cerulean City, Starmie was used to battle against Ash's Pidgeotto. Starmie uses the water enviorment to its advantage by diving into the water and resurfacing when the Pokémon least expected it. It got blown into a wall by Pidgeotto's Gust attack. Before any further action could be made, the battle was stopped because of the intervenance of Team Rocket.
In The School of Hard Knocks, Starmie's gem gets broken during its fight with Giselle's Graveler when it pushed itself passed Starmie's Water Gun by spinning at an incredible pace and smashing onto Starmie. Its gem, however, regenerates at some point because in its next episode appearance, its gem is fully restored.
- Ikue Ōtani (Japanese and English)