Sneasel guarded Ho-Oh's sacred flame, along with a Machoke and a Machamp, to prevent anyone from taking it.
Team Rocket, who tried to obtain this flame, encountered the three Pokémon. Jessie sent Arbok to battle it, but Sneasel easily slashed it. James and Jessie were impressed by it, though Meowth doubts that. Jessie tossed Meowth in the battle, who used Fury Swipes, but missed and got scratched. Thus, Machoke and Machomp easily blasted the three away. As Harrison and the heroes came, Ash sent Totodile to battle Sneasel. Totodile went to use Water Gun, but missed and got hit by Feint Attack. Totodile repeated its attack, but missed and got hit by Shadow Ball. The attack blasted Totodile onto Ash, who fell down and bashed into a tree. As the heroes returned to battle the three Pokémon, Team Rocket arrived to capture Sneasel.
Meowth, dressed as a Sneasel, approached Sneasel to give it a "present", containing a smoke ball, set to detonate. However, Meowth, fearing he would be replaced, warned Sneasel of its contents. Sneasel simply slashed Meowth's costume, and the bomb got detonated. James and Jessie grabbed Sneasel, wishing Meowth goodbye, as they abandoned him. To their shock, they actually grabbed Meowth, who pierced their balloon, causing them to blast off. Sneasel then turned to Harrison, who sent Blaziken. Blaziken used Quick Attack to hit Sneasel, who retaliated with Shadow Ball. Blaziken avoided the attack and fired Flamethrower, then used Fire Punch to knock Sneasel down, allowing Harrison to capture it.
Harrison used Sneasel to battle a Trainer's Machoke. This allowed Harrison to pass into the next round of the tournament. Sneasel was used to battle Ash's Pikachu in the quarter-finals of the Johto League. Sneasel quickly evaded Pikachu's Thunderbolt and defeated it with Metal Claw. Ash then sent Totodile to use Water Gun, to which Sneasel dodged that attack. Sneasel closed in on Totodile to use Metal Claw, but Totodile bit its arm and hit Sneasel on the ground, before defeating it by whacking it with its tail.