Omegamon/Omnimon is basically the Terminator here, since he beats almost everyone he fights, usually other megas, and only those who ran away survived fighting him.
No mention of his battle with WarGreymon and MetalGarurumon? Aside from being well animated, it has the double advantage of being a monumental, legendary clash for the franchise featuring one of the most legendary digimon... and the two equally infamous monsters that comprise him.
But the real crowning moment is at the end, where we see how he's come full circle. After spending the majority of the movie working to wipe out the X-Antibody digimon, he accepts Dorumon's Heroic Sacrifice, becoming such a being himself and delivering an epic Shut Up, Hannibal! speech... to a character that has been entirely silent for the entire movie. Then, he delivers a final strike to Yggdrasil, saving and restoring the entire Digital World.
Omegamon X gets one move in the entire film, and that move is punching out the Digital World's God.
Dukemon/Gallantmon gets a special mention, since he is the first to question his master and (Huge spoilers ahead) Stops Omegamon from killing Dorugamon, by challenging him to a duel (obscured by clouds, sadly). Suddenly, he let's himself be impaled because, and I quote "There was something I wanted to check" while completely calm thus making Omegamon doubt his master for the first time. For itself, that would usually be enough, but he goes further: He returns from the dead stronger (and note he is the only example in the franchise who had planned it), having obtained most of the answers he wanted. Then he tells Dorugreymon how he can save the world, while casually massacring the invasion force. Then, he opens a portal to Yggdrasil, thus allowing him to save the world. He then reassures him that he would stand his ground against the thousands of invaders.So not only did all of his plans succeed, singlehandedly allowing for the world to be saved, by the end of the movie he is also the only that understands why the events of the movie took place.
MetalGarurumon X pulling a Hold the Line against a seemingly endless swarm of Death-X-DORUGreymon to allow all the other rebels to escape. And demonstrating the epitome of More Dakka in the process.