Houndoom debuted in Pop Goes The Sneasel, where it was first seen walking beside its Trainer. It listened to the story of Ho-Oh's Sacred Flame and joined Harrison and the others when they went to retrieve it from a territorial Sneasel. It jumped in to battle Sneasel's Machop crony, repelling it with Flamethrower. On the second attempt, Houndoom fought alongside Phanpy against the Machop and Machoke, using Headbutt to take down the latter, then catching it on its horns and throwing it over the hill, out of range of the battle with Sneasel. It appeared willing to battle Sneasel, but Harrison chose to use Blaziken instead.
During Harrison's battle with Ash in Can't Beat the Heat!, Houndoom came out as his fifth Pokémon to fight Snorlax, who had already taken down Hypno and Steelix with little effort. Houndoom proved to be very powerful, using Counter to reflect Hyper Beam back onto it at double the strength, knocking out Snorlax in a single hit.
Houndoom fought Ash's Bayleef, where its significant type advantage showed off as it roasted Razor Leaf with Flamethrower. However, Bayleef cunningly used Vine Whip to muzzle Houndoom and prevent it from using Flamethrower or Bite. Bayleef threw Houndoom onto the ground and Body Slammed it, taking it out of the match.
Houndoom battled and lost to Jon Dickson's Rhyhorn after being rammed by the Spikes Pokémon. As Harrison's final Pokémon, Houndoom's loss caused Harrison's elimination from the tournament.
