Butterfree

Butterfree made a cameo appearance in Ash Ketchum vs Charles Darwin

Information on the Cameo
Butterfree is a Bug-type Pokémon based on the real life insect known as the butterfly. Butterfree was the first Pokémon that Ash caught. He lets his Butterfree leave in the episode known as Bye-Bye Butterfree.

Appearance in the Battle
Butterfree flies across the scene when Ash Ketchum says Reese's Pieces.