You found a Venusaur!
Venusaur, known in Japan as Fushigibana (フシギバナ?), is a Grass/Poison type Pokémon species in Nintendo and Game Freak’s Pokémon franchise. Created by Ken Sugimori, Venusaur first appeared in the video games Pokémon Red and Blueand subsequent sequels, later appearing in various merchandise, spinoff titles and animated and printed adaptations of the franchise. Venusaur is capable of Mega Evolution, which allows it to transform into Mega Venusaur.