In Which Wurmple's Which?, Wurmple’s Trainer, May argued with Jessie over which one of them had the better Wurmple. After Max concluded that the two Wurmple are exactly the same, they begin battling, but Team Rocket were sent blasting off by Pikachu. May soon realized that she has Jessie's Wurmple and that she has hers. While with Team Rocket, Wurmple caused trouble for them by eating their little food, proving to be far more gluttonous than Jessie’s Wurmple. Eventually, Wurmple was handed back to May in exchange for Jessie’s Wurmple.
In the episode A Corphish Out of Water, May and Jessie once again pitted their two Wurmple against each other in battle, where they both simultaneously evolved, into Silcoon and Cascoon respectively.
As a Silcoon
Four episodes later, in Seeing is Believing!, Silcoon once again battled Cascoon, in an attempt to prove to Jessie that her Pokémon was not a Silcoon, and in the process evolved into Beautifly. Later in the episode Jessie’s Cascoon evolved as well and two once again fought, with Beautifly coming out on top.
As a Wurmple, it would gorge itself on food and then fall asleep, unlike Jessie's more sedate and well-behaved Wurmple. It was quite a lazy little Pokémon. When it evolved to both its latter stages, however, it became more calm and mellow. As a Beautifly, it often likes to sit atop May's head, and it appears to only do so to those it considers her friends, such as when it landed on top of Ash's head after it and May came to Sinnoh.