All bug pokemon which go through a cocoon phase suffer an extreme loss of mobility, which dramatically hinders their ability to resist predation, and have learned to harden their cocoons in an often doomed effort to live long enough to evolve. Spewpa are far better than their counterparts at protecting themselves, for they also learn to block attacks outright, leading many predatory pokemon to walk away in frustration. Although nearly any trained pokemon can easily defeat the Spewpa, it is enough of a defense to give them a significant evolutionary advantage; while Butterfree, Beautifly, Beedrill, and Dustox are geographically restricted, Vivillon can be found all over the world.
Spewpa's bodies are not only extremely tough, but also remarkably skilled at concealing damage. Although a flying pokemon may cause internal injuries with a peck, they do not show as a scratch on either Spewpa's oversized head or white, fluffy body whose only feature is a shifting array of dust. This illusion is sufficient to fool many predators, who give up their attacks when convinced they are doing no damage, but tragically, it can fool their trainers as well.
Spewpa are poor at damaging foes, and therefore are rarely sent into battle, preferring to learn through practice and watching their comrades. But there are times when trainers use their Spewpa as a last resort, or who try to they take advantage of their strong defenses in combination with continuous attacks from their teammates; in these matches, it is extremely challenging for either trainer to tell when a Spewpa has fainted. Tragically, there are far too many reports of unconscious Spewpa who continued to face attacks until they died on the battlefield, and only a trip to the pokemon center revealed to their trainers this awful truth.
