Just fought of this being a fun idea to discuss, as many of us were disappointed that for characters outside Naruto and Sasuke didn't get much screen time to fight particularly in the later half of part 2 during the war. As the title implies 1 added fight for any character you can think off that you wanted to see get an extra fight in the manga and why(figured this would be easier since most of us would of given this to Sakura if we could only do one character).
Examples I have are I wanted to see Lee fight kimimaro during the war because a rematch would of been nice and Neji vs his father because it could of brought some closer to the hyuga sub plot.
Now if you want to you can want one solo fight and ones tag team/group team fight as two separate things if that makes it easier. For example I could want a Sakura vs Konan fight because these two character were supposed to be parallels to each other and would be interesting to see them interact. While at the same time have Naruto team up with Sakura against Sasuke, because we excepted Sakura to help in some way.