The Powerpuff Girls (1998)

S01E07 Buttercrush

Buttercup finds herself head over heels for Ace, the leader of the Ganggreen Gang. But when the gang takes advantage of her feelings to put Blossom and Bubbles in peril, Buttercup realizes she must spring into action. She rushes to save her sisters and teaches the boys a valuable lesson about what it truly means to have a "crush."