Flying Rhino Junior High is a Canadian cartoon series created by Nelvana that aired from October 1998 to January 2000. It focuses on four children attending a school where the principal is a rhinoceros, who find themselves saving their school from chaos created by a student bent on revenge for getting a "D".
Comic Book Chaos (S01E08)
Earl creates four comic book villains to attack the school. The kids beat every one by exposing their weaknesses, and finally trick Gravity Girl into using her power against herself, causing her weight to increase.