Vigoroth is the evolved form of Slakoth. When Slakoth evolve into Vigoroth, their minds cannot comprehend the boost in thinking speed, and so they go insane. They like to yell at each other and run around. Since their hearts beat at a ten-fold tempo, they yell too quickly for anything other than another Vigoroth to understand, and they have the power to become "invisible" by moving so fast that no one can see them. Not surprisingly, Vigoroths are feared throughout the world of Pokemon. Vigoroths are very rare, so lots of people use the Lazy Stone to make Slakoth evolve into Slaking.