All of Alpha and Zetto's fight in the finals of the X-Cell Tournament, including them working together to stop an interrupting Giga.
Episode 60, where Alpha for the first time ever, takes full control of Kagemamaru's power and proceeds to fight the D-Bug. The music being set to the first one or two minutes of Travel Demon especially helps.
T.O.M.E (The Remake) provides examples of:
Alpha's battle against Rockoon and Doubling and beating them with no effort.
It was especially epic that Zetto seemed casual and expected a fight against Alpha's inner demon, and got a MASSIVE upgrade compared to his original version. Highlights include Alpha's Oh Crap face and the last thought his inner demon had as he was falling: "how".
Martin LittleKuriboh Billany's performance as Nylocke throughout the whole episode.
Nylocke, Gamecrazed, Elescope and Hyprelynx vs Tigerlilly, and winning. Nylocke's Rousing Speech only added to it.
Neomutant puts up the best fight against Demon Alpha short of Zetto'sCurb-Stomp Battle. He lost, but he certainly put up a fight.
Flamegirl's standing up to Demon Alpha and stopping him from rampaging like last time. She does it alone, without hesitation and stops it in the end with a Cooldown Hug.