In Year 2, Harry gives Riddle an awesome"Reason You Suck" Speech ending with Harry declaring himself the Heir of Slytherin.
Harry gets a big one in Year 4. During the Third Task of the Triwizard Tournament, unlike in canon, all four champions make it to the center of the maze. Harry faces off against Fleur Delacour and manages to best her despite being at least three years her junior in terms of magical study.
Though only after Fleur breaks her arm and has to fight left-handed.
The duel between Cedric and Viktor Krum, though we only see brief bits of it, is no less epic. The two are trading spells at a furious pace, so much so that Harry is left in awe.
Harry then manages to distract Cedric and grab the Cup before Cedric can.