Jessie caughtWurmple in All in a Day's Wurmple, as did May. Several episodes later, in Which Wurmple's Which?, both Wurmple were temporarily switched, but were returned to their proper Trainers by the episode's end. In A Corphish Out of Water, Jessie's Wurmple evolved into Cascoon while May's evolved into Silcoon; Jessie believed hers was a Silcoon as well. Four episodes later, in Seeing is Believing!, Jessie's Cascoon evolved into Dustox, soon after May's Silcoon evolved into Beautifly. While Jessie was at first disappointed that she did not have a Beautifly, she almost immediately came to adore her new Dustox (in the Japanese version, she called her Dokucale-chan on more than one occasion). In the English dub, Jessie has called her Dustox-Dear, and when she throws her Poké Ball, she has also called her "my dear Dustox".
Dustox was also Jessie's secondary battling Pokémon. She was usually used alongside Seviper, but she had also been used alone. She appeared to be fairly powerful, but as Team Rocket are the villains, she was usually defeated.
In A Stand-Up Sit-Down!, Jessilina decided to face Dawn to practice for the Hearthome Contest. However, it was Zoey who accepted the challenge. Jessie used the combination of Dustox and Seviper and her idea was to make Dustox use Poison Sting and then to make Seviper use Poison Tail on Dustox's Poison Sting, making it spin and adding extra-power to it. Brock even said that that was a smart combination. However, that didn't work as Zoey's Glameow countered with Iron Tail, making the combination go to the other side. Zoey's Shellos then used Mud Bomb, breaking the combination of Poison Sting and Poison Tail. Dustox and Seviper were then both easily defeated by Zoey's Glameow.
In Team Shocker!, Dustox was used in the Solaceon TownPokémon Contest. During the Performance Stage, she used Whirlwind to lift Jessie off the ground, leaving the crowd astounded. She kept Jessie floating for a while and then used Psybeam to create a thick green smoke which covered the entire stage. When the smoke was cleared, it revealed Jessie and Dustox smiling and posing before the audience. The performance was well-received by the panel of judges and, when the results were announced, Jessie appeared among the Coordinators advancing to the Battle Stage. There, Dustox was able to defeat her first two opponents to reach the finals, where she went up against Kenny's Prinplup. She managed to use Prinplup's techniques against him to win the battle, earning Jessie her first Contest Ribbon. Ever since, Dustox has been wearing Jessie's hair-ribbons that she wore in that Contest.
In Crossing Paths, during the Dustox Crossing, she fell in love with a Shiny Dustox owned by Austin. Jessie tearfully decided that Dustox had to go with the others, despite everyone's protests, but, since Dustox was loyal, she didn't want to. Seeing that Dustox was facing the same dilemma Jessie once was, about to throw away her chance of finding her true love to be with friends, Jessie had to shatter Dustox's Poké Ball to let her go. Dustox then went to live with other Dustox and start a family, giving Jessie the hope of finding her own soulmate.
As a Wurmple, she was very sedate and well-behaved, unlike May's Wurmple who was gluttonous and a bit disobedient. When she evolved she stayed well-behaved and was very loyal to Jessie. They had a very strong connection with each other, most obvious upon Dustox's release when Dustox wouldn't go with her mate and refused to leave Jessie's side.
Description: Dustox uses Poison Sting towards the sky. When the purple darts start falling down, Seviper hits them with Poison Tail, making them spin very fast. The spinning darts head towards the opposing Pokémon at great speed with the extra power that the Poison Tail added. The combination was used during a Double Battle against Zoey's Glameow and Shellos.
The yellow ribbons Dustox wears in the episode she was released are similar to the ones Jessie wears when she is disguised as Jessilina when competing in Contests.
Once her Cascoon evolved into a Dustox, Jessie's team didn't change for over 250 episodes until she released Dustox, not counting temporary changes.
Dustox is the only Pokémon in the anime belonging to a main character to have its Poké Ball broken permanently.
Out of all of Team Rocket's Pokémon, Dustox has used the most different types of moves, at six different types used.
Excluding her temporary Pokémon, Dustox is Jessie's only Pokémon that is part of a three stage evolutionary family.