Trevor received Charizard as a Charmander for his first partner Pokémon from Professor Sycamore prior to Summer of Discovery!.
Charmander debuted in Summer of Discovery!, where it ran downstairs and greeted Ash and his friends along with their Pokémon. Charmander had a First-Touch Battle with Clemont's Chespin. It won after accidentally catching Chespin's tail on fire.
In Day Three Blockbusters!, Charmander starred in a Pokévision video along with its Trainer, Tierno, Shauna, and their Pokémon.
Charmander batting alongside Squirtle and Bulbasaur
In Battling Into the Hall of Fame!, it was sent out in a Team Battle against Ash, Serena, and Clemont. It was the first Pokémon of Team Squirtle to get defeated when it was hit by Pikachu's Thunderbolt.
In A Legendary Photo Op!, it was revealed to have evolved into a Charmeleon. Trevor sent it to battle Ash's Fletchinder. Despite putting up a fight, it was defeated by Fletchinder's Steel Wing. Later, at Mt. Molteau, Trevor used Charmeleon in a Tag Battle alongside Ash's Fletchinder against James's Inkay and Jessie's Gourgeist. Their battle disturbed a Moltres slumbering in the volcano and the battle was interrupted. Charmeleon attempted to battle Moltres to calm it down but it was unsuccessful.
Charmeleon reappeared in Tag Team Battle Inspiration! alongside its Trainer, while he took a picture of a wild Lairon.
Drought activated as a Mega Charizard Y
In A League of His Own!, Charmeleon was revealed to have evolved into a Charizard. It was used to battle Alain's Charizard in the first round of the Lumiose Conference. Trevor's Charizard opened with Fire Spin, which Alain's Charizard dodged by flying in the sky. Alain's Charizard then retaliated with Flamethrower, with Trevor's Charizard blocking the attack with Dragon Claw. Trevor then revealed his Key Stone and Mega Evolved his Charizard into Mega Charizard Y. Upon Mega Evolving, Mega Charizard Y's Drought Ability activated, creating harsh sunlight and powering up all of its Fire-type moves. Trevor's Mega Charizard Y then attacked with Heat Wave, but Alain's Charizard was able to block it, creating a water shield by slamming its tail into the nearby stream. Trevor's Pokémon then flew up to attack with a Dragon Tail, but Alain's Charizard dodged the attack. Alain's Charizard then Mega Evolved as well and countered a Fire Spin with Flamethrower, creating a cloud of smoke. Trevor had his Charizard fly into the sky, but Alain's was able to spot it through the smoke and defeated it with a single hit from Flamethrower.
In A Towering Takeover!, Charizard and Trevor joined the fight against Team Flare. It was later seen at the Pokémon Center, helping the citizens of Lumiose City. It was also seen watching the battle against the Giant Rock unfold on television in Rocking Kalos Defenses! and Forming a More Perfect Union!.
Charizard's Charizardite Y
As a Charmander, Charizard was an energetic, if not hyperactive, Pokémon, who loved to battle. It was often seen running around when not in battle.
Similar to Ash's Charmeleon, Trevor's Charmeleon was very aggressive to the point that it attacked its own Trainer at one point and even other Pokémon. However, during battles it gladly accepted Trevor's commands and was also shown to have retained traits it had when it was a Charmander, such as its love for battling others to test its strength.
