Let's ignore the first scenario for a moment. How does Tsunade win scenario2?1- Tsunade wins.
2- Tsunade wins.
3- Kamui GG.
Like Kakashi said himself on more than one occasions, he doesn't fall for the same techniques twice and it has been repeatedly proven in the manga on multiple occasions, in almost all his fights including the final one against a god like Kaguya where he clearly outperformed the entire team7 and Kaguya herself in terms of battle strategy and input. So give him knowledge, and Kakashi will win all match-ups against opponents who don't terribly outclass him in overall power, and Tsunade isn't one of them, far from it actually considering he is the most versatile and tactical fighter of the two. How she win in people's minds here is a mystery for me
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 theYou must be registered for see linkst 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.
Gai has never known tsunade before she came to the leaf.
He only met her when she came to the village with Jiraiya and Naruto.
Tsunade wins them all.
Tsnade attacks are fare to destructive for Kakashi to have the time to perform a large scale Kaumi to effect her.
So me scan when Kakashi can use the jutsu while being pursued, he will be trying he hardest to just avoid her attacks.
Lighting attack seems to be iffy too, logically if they make contact with her she should be able to redirect Body Pathway Jutsu back to Kakashi, paralyzing him, then she kills him.