Pokémon (1997)

S8E50 Caterpie's Big Dilemma

Team Rocket launches an assault on an inventor's lab, causing his Caterpie to accidentally consume a mysterious experimental substance that causes it to grow to monstrous sizes. Things take a turn for the worse when Caterpie evolves into Metapod, and then rapidly transforms again into Butterfree, escalating the chaos even further.