Butterfree

Butterfree (Japanese: バタフリー Butterfree) is a dual-type Bug/Flying Pokémon introduced in Generation I.
It evolves from Metapod starting at level 10. It is the final form of Caterpie.

Metapod

Metapod (Japanese: トランセル Trancell) is a Bug-type Pokémon introduced in Generation I.
It evolves from Caterpie starting at level 7, and it evolves into Butterfree starting at level 10.

Caterpie

Caterpie (Japanese: キャタピー Caterpie) is a Bug-type Pokémon introduced in Generation I.
It evolves into Metapod starting at level 7, who evolves into Butterfree starting at level 10.