Daisy's Dewgong made its first and only appearance in the episode The Misty Mermaid. It was in an underwater ballet written by Violet, one of Misty's three sisters.
After successfully attacking Jessie's Arbok, it evolved and afterwhich froze Team Rocket with its Ice Beam attack. In the end, the show was saved by Daisy's Dewgong. Unfortunately it hasn't been seen since and most likely remains at the Cerulean City gym.