While it's understandable that you would like to see those fights happening (heck, who doesn't? And some of those are probably a given), probably you'd like to provide your opinion as to why you want it or your hypothesis on the scenario? It helps to foster exchanges of countless exciting thoughts.
I'd like to see Lea and Saix fight, too. I think at the time they cross path again, Lea would try to convince Saix to renounce his allegiance with Xehanort, but for his words to fall on deaf ears. Or you know, their big battle could be the culmination of their previous little encounters in which their ideals conflict, similar to their confrontations in Days but getting progressively more and more violent in nature. Then, finally, they duke it out; Saix attacking as relentlessly as he always did, while Lea is reluctant at first.
I'd also like to see anyone versus Xigbar, probably Sora. As much as I love the guy and his art of trolling, I'd so much like to see how much his demise would derail Xehanort's plans. I'm not positively sure that it would do anything, though, seeing that Xigbar is likely to be in the final confrontation in the Keyblade Graveyard where everything is about to go out with a bang and that defeats of various members are due, timely, and expected anyway.
I'm pretty sure I have several more fights I'd like to see, but I'll post them up later if I'm not lazy to do it.