Kisame poops on her. He is a horrendous match up for tsunade. Not only does samaheda drain her chakra, it slashes/cuts/causes severe injury. Hence she will be forced to keep healing and waste chakra, and have her chakra drained simultaneously. He wins without much difficulty.
? He practically made a ocean(exaggeration of course but you get the point) which tsunade has no counter for. Water clones, %30 clone's speed is enhanced due to surfing on the water, tsunade won't be able to touch him, she's prone to sharks at any moment.
I think kisame wins with med-high diff .
however , just curious , would tsunade's CES be severely weakened upon approaching kisame's skin at proximity ?(fused with samehada)