Dustox, the Toxic Moth Pokémon. Dustox is the evolved form of Cascoon and is drawn toward bright light. When flapping its wings, it will scatter a poison dust.
– Ash’s Pokedex
Despite Gen I already had a moth Pokemon in Venomoth, Gen III introduced another moth, Dustox. Dustox and Beautifly both evolve from Wurmple, depending on the Pokemon’s IV. Despite having wings, Dustox is not part flying.
In the anime, Jessie had a Dustox (while May had a Beautifly). She used it in battle as well as contests. I remember in one episode, Jessie’s Dustox turned huge from this scientist’s candy thing, and Team Rocket were able to ride on it.
Stat-wise, Dustox has decent Defenses, but not great Attack stats or Speed.