Seviper first appeared in Swanky Showdown with Swalot, in the opening ceremony of the Battle Frontier. She was then used in an exhibition tag battle with Spenser and his Crobat. She started things off by targeting Electrode since it wasn't a Poison-type, so Seviper teamed up with Crobat to weaken it and as soon as Electrode was on the brink of fainting, Swalot jumped in and put Seviper to sleep. She woke up immediately and dug a hole underground. Lucy revealed this when Swalot went for Hyper Beam. Seviper burrowed back up and single-handedly defeat Electrode and Swalot, declaring Lucy and Spenser as the winners. When Emerald crashed the press conference, Seviper wrapped herself around the young Trainer so that he wouldn't escape.
In Gotcha Where I Wantcha, Glalie, she was seen with Lucy while Lucy told Greta that she would be the next Frontier Brain Emerald was going to face after Noland's loss. When Emerald was sleeping in mid-air, with Brandon and Tucker tied to the Battle Pike's fangs, Lucy sent out her Seviper to cut them free. As Emerald reached the 139th room and opened the doors to the next room, Seviper appeared along with Lucy's other Pokémon when Lucy took her station. Seviper was the first Pokémon that Lucy sent out in her battle against Emerald when he challenged her at the end of the Battle Pike. She went up against the Blissey Emerald borrowed from Crystal earlier. During their battle, Seviper was hit by Blissey's Seismic Toss but it wasn't long until Seviper used Poison Fang by seeping poison out from her fangs and the poison touched Blissey which badly poisoned her. Lucy then switched out Seviper and Shuckle took her place when Blissey was about to attack even though she was in her poisoned state, which forced Emerald to switch to Starmie.
After Lucy's Shuckle and Milotic were subdued in the same battle, she uses Seviper again where she battled Emerald's Rapidash. During the battle, Rapidash was beat, leaving them both with one Pokémon. Blissey was able to withstand much abuse with its inherently high defense, but eventually lost ground and was beaten. As the other Brains were about to rejoice on Lucy's victory, Rapidash awoke and promptly defeated Seviper with its Overheat attack.
Seviper was later seen with Lucy when the Frontier Brains were looming over an unconscious Noland after Guile Hideout knocked him out cold. She was also seen standing next to Lucy when Lucy and the other Frontier Brains stop Emerald when they were questioning Sceptile's whereabouts.
In Skirting Around Surskit I, Lucy uses Seviper against Guile Hideout alongside other Frontier Brains' Pokémon but lost as Guile easily sent them flying with a swing from his sword. During Emerald's battle in the Battle Dome, Seviper helped organize the crowd when they were entering the place. Later, Seviper helped out protecting the people from the rampaging rental Pokémon and dealt with a flood caused by Guile's Kyogre-shaped monster.
As a powerful and versatile Pokémon, Seviper is Lucy's first choice for battles. Like her Trainer, Seviper is confident in her strength and battle skill. She is able to defeat many opponents with her poison and is often seen beside Lucy.
Seviper appeared in Queen of the Serpentine!. After Lucy threw a red rose projectile at Team Rocket's balloon, she sent out Seviper to battle them while Jessie sent out a Seviper of her own. True to Barbara's word and confidence, Lucy's Seviper managed to overpower Jessie's and it was sent crashing into Team Rocket. Seviper finished them off by revealing an ability to use Flamethrower, which sent Team Rocket blasting off.
During Ash's match with Lucy in the Battle Pike, Lucy sent out Seviper as her first choice and went up against Ash's Donphan. Although evenly matched at first, Seviper managed to hold its own against Donphan and countered and dodged every move that Donphan made. However, this wasn't enough as thanks to Donphan catapulting itself upwards by hitting a rock after using Rollout, Seviper was defeated and Lucy was left with one Pokémon.
Personality and characteristics
Seviper and Lucy
Lucy appears to trust Seviper the most out of all her Pokémon, as seen when she owned several things in the shape of Seviper such as the Battle Pike and her red rose projectile. This was also demonstrated during battle, when Lucy closed her eyes at one point and knew by heart what attacks the opponent was going to throw at it. Barbara even pointed out Seviper's strengths, which were shown when it single-handedly took out Team Rocket.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
In other manga
Pokémon Battle Frontier
Seviper and Lucy in Pokémon Battle Frontier
Lucy's Seviper appeared in The Predestined Battle!. It was first seen with its Trainer when she went up to Enta and had a conversation with him. Later, it battled with Enta's Milotic first where it managed to daze it with an unidentified attack. Afterwards, it faced off against his Zangoose after both sides were down to one Pokémon. Since both of them are natural enemies to each other, it was hard for Enta to have Zangoose to listen to him. However, Zangoose was finally able to listen to Enta after he jumped in the way of a Poison Tail attack launched by Seviper. With Zangoose and Enta in sync with each other, Zangoose was able to defeat Seviper with Crush Claw.