Charizard

Ash Ketchum has a Charizard that he obtained as a Charmander in Charmander the Stray Pokémon. It evolved into Charmeleon in March of the Exeggutor Squad and quickly evolved again into Charizard in Attack of the Prehistoric Pokémon, where Charizard saved Ash from the claws of an Aerodactyl. From the time of its becoming Charmeleon to the Orange Islands episode Charizard Chills, Charizard refused to obey Ash and was a burden which Ash still cared for. After Charizard Chills, however, it became one of Ash's strongest Pokémon, perhaps even stronger than Pikachu. Ash left Charizard in theCharicific Valley with Liza in Charizard's Burning Ambition. It has returned to visit and battle for him on several occasions since then.