From Bulbapedia, the community-driven Pokémon encyclopedia.

Chikorita is a species of Pokémon. It may also refer to specific Pokémon of that species:

• A Pokémon which belonged to Ash Ketchum before evolving: Ash's Chikorita
• A Pokémon which belonged to Casey before evolving: Casey's Chikorita
• A Pokémon which belonged to Vincent before evolving: Vincent's Chikorita
• A character in Pokémon PiPiPi Adventure: Chiko