Ok here are the facts:
One thing that I'm sure all of you will think about when it comes to Kisame vs Kakashi...Kakashi obviously has very little chakra and Kisame can steal his chakra so this would imply that Kisame is the worst possible opponent for kakashi because he could theoretically kill him just by draining his chakra to absolute zero but...Kakashi has the sharingan so he would be able to see right away that Kisames sword is stealing his chakra so then he would come up with a way to defend against that, and heres another point that Ive never seen mentioned before in a kakashi vs kisame fight, kakashi uses lightning style while kisame uses water so his lightning would travel through the water and spell trouble for kisame, therefore kakashi can counter his most powerful moves, although kisame could suck up his chakra so he cant use lightning style and then proceed to use his most powerful techs, this is true but kakashi is smarter then that and would catch on to his strategy too early, then their is the fact that with the sharingan kaakashi can copy most if not all of kisames techs,kakashi seems especially good at water style anyway. Yeah I think Kisame is stronger then kakashi in terms of battle power but honestly conisdering the kind of fighter kakashi is, he would win. He probably wouldnt even have to result to his MS to win but hes still got that for backup.
Now Tsunade could handle Sasori without a doubt, she can smash through his puppets with ease and heal any wounds and also stop the poison but the only problem is if she ends up running low on chakra before she gets through all of sasoris puppets...tsunade would win this fight for sure but if kakashi were to lose his fight against kisame then Im not so sure if a wounded tired low chakra level tsunade could finish kisame. If it was the other way around and Kakashi fought sasori...well he wouldnt win plain and simple, 100 puppets + plus the third kazekage puppet with kakashis low chakra level? sorry but thats not happening. Kisame COULD defeat Tsunade but with her summoning abilities she could stay above water and I believe she could pull off a win. Although she will be greatly weakened by Kisame even if she wins still Sasori is a fairly easy victory for her win he's at full health so with the damage he would sustain from Kakashi, tsunade would win.
So either way, no matter how they conduct this battle I say "The will of Fire" prevails. Although as I explained its possible "Desert Mist" could win. Still an epic battle either way.