Jessie caught Seviper in A Tail with a Twist after initially being impressed with its sneaky and aggressive demeanor. It had defeated Ash's Treecko earlier in the episode, which is why Jessie wanted it so much. Although Seviper was intelligent, and outsmarted Team Rocket's multiple attempts to ensure its capture, Jessie caught Seviper after it had bitten off a chunk of her hair, mangling poor Seviper with her "Fury Swipes" and "Mega Kick".
Seviper is, along with Yanmega, Jessie's primary battling Pokémon, often seen battling alongside James's Cacnea in Hoenn and later James's Carnivine in Sinnoh. While shown to be fairly powerful before being caught by Jessie, after it fell into her command, it suffered the inevitable fate that all Team Rocket Pokémon face- defeat by Ash or another good character. In the episode Zig Zag Zangoose, Jessie and Seviper were determined to win a battle against Seviper's mortal enemy, a Zangoose belonging to the trainer Nicolai.
Seviper has also entered a few contests. In Mademoiselle Jessica's contest debut, in All Things Bright and Beautifly!, Seviper was Jessie's chosen Pokémon to enter the contest, but miserably failed to pass the Appeal Round, as Jessie didn't prepare herself to the contest, and ordered Seviper to use attacks that Seviper can't learn, such as Blaze Kick. She is then seen apologizing to it, meaning she does care about Seviper.
In Settling a Not-So-Old Score!, Jessalina used Seviper in the Appeal Round. Not much of the Appeal was seen, because while Seviper was performing it, Dawn was thinking about her Pachirisu's Appeal, focusing the atention on her, not in Jessie. However, Kenny stated that Seviper was being quite good. Even though we couldn't see most of the appeal, we see how it finishes: Jessie ordered Seviper to perform Wrap and Bite on Jessie herself, and thus, amazing the crowd.
In the episode A Stand-Up Sit-Down!, Jessalina decided to face Dawn to "practice" for the Hearthome City contest. However, it was Zoey who accepted the challenge. Jessie used the combination of Seviper and Dustox 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 added 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 going to other side around and then Zoey's Shellos used Mud Bomb, breaking the combination of Poison Sting and Poison Tail. Seviper and Dustox both were then easily defeated by Zoey's Glameow.
In Dawn's Early Night Seviper and Dustox were used in the Battle Round of the Hearthome City contest and lost against Nando. Not much of the battle was seen. In DP123 it was also used in the battle round of a Contest and it was quite succesful until it lost to Dawn.
Since Jessie has caught Yanmega, Seviper isn't seen in as many battles as before.
It is also used as Team Rocket's escapist rogue to blanket the area in Haze, replacing James's Weezing's duty to steal innocent Pokémon under the shrouded premises.
