His handicap in Event 51 is a lot higher than in Normal Adventure mode. His attacks are all the same as Bowser's, but with more power, obviously, and side-effects (including explosions, earthquakes, ice and others depending on the attack). I'd assume that when you've hacked your way into using him, his attacks would be assigned to the same buttons as Bowser's. The easy way to win Event 51 is to get rid of Giga Bowser first by using Jigglypuff's Rest, but I really have no problems racking up his damage counter in Adventure and sending him flying.
