Zippo was introduced as a Charmander during the Indigo Plateau Conference, breaking open a wall in a van Team Rocket trapped Ritchie and Ash in with Slash when Ash's Bulbasaur couldn't do it on its own. Later, during Ritchie's battle with Ash, Zippo was sent out against Ash's Pikachu when Ritchie's Butterfree, Happy, was defeated. Even though Pikachu dodged multiple Flamethrowers, he wasn't able to keep up and lost to Zippo's Tackle. Zippo's next opponent was Charizard. Zippo ran away from Charizard's far stronger Flamethrower after using Flamethrower itself. This caused Ritchie to recall it.
In Friends to the End, it was briefly shown battling Assunta's Rhydon. It was revealed to have been knocked out later when Ritchie's last Pokémon was shown to be Sparky. In that same episode, it saved Ash's Pikachu along with Sparky when they were captured by Team Rocket.
In Oaknapped!, Zippo was sent out to take on Butch's Mightyena. It used Flamethrower on Mightyena but some of the flames landed in Professor Oak's hair. Zippo then used Fire Spin on it, also hitting Cassidy's Sableye. The opposing Pokémon landed on their Trainers, leaving Sparky a chance to blast them off with Thunder.
Personality and characteristics
Zippo and Ritchie
Zippo, as a Charmander, was willing to battle any opponent, including ones that have evolved as shown when it was battling Charizard.