Vigoroth are considered among the most difficult pokemon to train, even though they are fairly powerful and will obey any command except one: Rest. These pokemon are awake twenty-four hours a day and spend none of those hours in anything remotely approaching relaxation. The pokeball, so often a means of ensuring a trainer's rest as much as their pokemon's, can not contain them long. Most trainers install exercise equipment near their homes or take their Vigoroth to a park to give them something to do at night, but they must still train themselves beyond apparent human limitations simply to keep up.
It was once said, as a way of explaining this restlessness, that Slakoth laze so they can store energy and when they can store no more they evolve into Vigoroth. When they become Vigoroth, they burn up that stored energy constantly until it runs out and they evolve (or perhaps devolve) into Slaking. Although this explanation is not taken seriously today, for Slakoth survive on a minimal number of leaves and Everstones can delay evolution, it does raise the question of just how Vigoroth can maintain such a vital spirit without eating like a Snorlax.
Some have speculated that Vigoroth are a sort of living perpetual motion machine and have taught them to turn generators in order to harness their nigh-infinite power. In some places they have replaced the Pikachu and Shinx normally used to create electricity, despite most of them not even knowing a single electric attack. Although the concept of a perpetual motion pokemon would require the laws of physics to be completely rewritten, research into Vigoroth metabolism has concluded nothing more than a striking dissimilarity to all other living things. The idea that Vigoroth defy thermodynamics has yet to be proven wrong.
