Kimimaro vs Hidan is debatable ( depending on the intel mainly ) but him beating Tsunade is not happening. She is the perfect counter against him due to the fact that Hidan will never have a chance to finish his ritual circle because of Tsunade's destructive aoe attacks.
The ritual circle is a trivial matter. With intel he knows of her AOE, just needs blood and then she is at his mercy. He can go anywhere he likes as long as he has her blood, can be a km away.
She's a perfect counter to him? Then he must be a perfect counter to her as well because
-she only does blunt damage which will only break his bones not dismember him (no need to show me a panel of an edo body exploding).
-her byakugou has a limit, and he is immortal.
With intel he knows about her Byakugou and can stab himself straight in the head. Tsunade won't be able to do a single thing with a rod jammed into her brain.
Only issue is he has to watch out for body pathway derangement that is literally all.
How he wins: With intel he gains her blood leaves her range and strikes himself in the head. Shutting her brain down.
How she can win: If she manages to hit him with body pathway derangement (and I'm giving Tsunade the benefit of the doubt here assuming Hidan's nervous system functions like a normal human, which it kinda has already shown it doesn't).