X-Men: Evolution (2000)

S2E5 The Beast of Bayville

Hank McCoy discovers that the serum he relies on to manage his mutation has lost its effectiveness, leading to increasing concern among his students about his volatile behavior. As Hank struggles to cope with his growing anger, the students grapple with their fear of what he might become. They must confront their anxieties and find a way to help him regain control before the situation spirals out of hand.