I had this dream that Ansem SOD was gonna fight against Xemnas, which made me wonder... Who would win? All of their forms would be allowed and they would also be as strong as their Data versions.
I personally belive that Data Xemnas would win against Data Xehanort, due to his endless lasers. But Final Ansem (his final form at KH1) would ultimately win. Xemnas would be able to defeat the cores, but he wouldn't be able to pull nor capture Final Ansem, while Final Ansem would be able to deflect all his lasers.
Well, first off, let's define exactly what limits we're dealing with here. Because many of the abilities and forms that Ansem and Xemnas are known for are not actually innate to them—some of their powers are only available to them in certain environments and situations. For instance, Ansem's final form in KH1 was the result of him merging with another gigantic Heartless, and without that Heartless, he would not have recourse to that form and all the abilities that come with it. The Guardian also presents a problem, because even though Ansem uses it up until DDD, he noticeably goes without it in KH3, whereas Terra-Xehanort does have it. This suggests that the Guardian is not an intrinsic feature of Ansem's abilities, but rather more like an ally that has to be shared between himself and Terra-Xehanort, so it's not clear whether we should count it among Ansem's movesets. But even if we do, for the most part, Ansem's roster of attacks, his battle strategy, and his weaknesses remain the same.
Likewise, many of Xemnas' iconic powers (like throwing buildings) only work if he's in The World That Never Was, because that world, being a Nobody world, is the only one which Xemnas would be able to control in that way, so that ability would be off-limits to him in any other arena. Also, many of his powers in his final KH2 stages are off-limits too, because so many of his moves there were a result of his infusion with the power of Kingdom Hearts itself, and also the result of his creating an entire pocket dimension of nothingness that he had complete control over.
So, I think perhaps the fairest comparison of their powers would be seen if we juxtapose their data battles from KH3. In this matchup, my guess is that Xemnas would probably be victorious, because not only does he have the agility and the martial arts moves to literally move circles around Ansem at any given time, but Ansem also doesn't have the speed or agility to dodge his laser move or many of his thorn-grabbing attacks. Ansem could probably get a few hits here and there at Xemnas with some of his DM moves, but on the whole I think Xemnas would have the upper hand regarding the main phase not only due to his greater speed and combat skills, but also due to his ability to teleport, to reach Ansem from across the arena with his nothing-thorns and also with the exploding lightning orbs, and also with his regular laser attacks, all moves which negate Ansem's chief strategy which is to keep distance from his opponent and use dark powers at them from a distance. Even though both Ansem and Xemnas contain abilities designed to reach enemies from far away, Xemnas is pretty much the only one of the two of them for whom close-quarters combat is equally efficient, and having to maintain the aforementioned distance is not as much a weakness for him as it is for Ansem.
Thanks for coming to my Ted talk.
