Casey's Meganium (Japanese: ナナコのメガニウムNanako's Meganium) is Casey's first and primary Pokémon. She obtained it as a Chikorita the day before Ash, Brock, and Misty arrived at Professor Elm's lab.
Casey first appeared with her Chikorita in The Double Trouble Header. It had just helped her to capture a Rattata when she met Ash and his friends. She challenged Ash to a Pokémon battle. Ash defeated all three of her Pokémon including Chikorita with his Charizard.
Casey and her Chikorita were next seen in The Bug Stops Here. She and Ash were competing in a Bug-Catching Contest when they were attacked by Team Rocket. Casey used her Chikorita, and during the battle, it evolved into Bayleef and sent Team Rocket blasting off.
Meganium shares a close bond with Casey, often being seen outside of its Poké Ball. It appears to share Casey's fighting spirit and enjoys her renditions of the Electabuzz fight song. Meganium is also a fierce battler, evolving into a Bayleef so that it could help Casey during the Bug-Catching Contest.
