After Dawn caught a Buizel, Zoey caught Gastrodon when it was a Shellos. Though somewhat shy, Shellos was close with Zoey, as it searched with Glameow help when she got injured. Zoey used it in some of her contests, including the Wallace Cup where it defeated a Mareep.
Zoey showed her third ribbon to Dawn after the battle between Ash and Fantina. Zoey told Dawn that Shellos came through for her to win it.
Prior to the Grand Festival, Shellos evolved into a Gastrodon and Zoey used it with her Lumineon to pass the first round and then the first round of battles. Gastrodon then battled alongside Glameow in the quarterfinals to help Zoey have a place in the semifinals.