When Team Rocket attacks an inventor’s laboratory, they startle his Caterpie into eating an experimental substance that enlarges it to dreadful proportions. Not wanting to harm local residents, the Caterpie flees to the outskirts of town before evolving into a Metapod. It enters this dormant state, however, just as its size is most needed—Team Rocket has used the same substance to enlarge their Dustox and use its enhanced power to further their nefarious schemes.