The only possible win for Tsunade would be the first scenario, and even then, I'd take Kakashi more times than not. He's been noted by Maito Gai to be the
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t there is and he's well aware of Tsunade's fighting style.
I feel he'd make better use of misdirection and trickery, especially utilizing his Lightning Clones. His stamina will not be drained because of the Sharingan and his chakra pool can be more finely used, allowing more clones, more offensive ninjutsu from a distance as well as Doton to keep Tsunade off her feet. He also used Suiton without a source as in Kakuzu fight, so he could add pressure with that or throw down a Water Wall when she attacks and fires off a Lightning Beast Running Jutsu to fry her.
Kakashi godstomps scenario 3.