Only way Tsunade can win this is if body pathway derangement works on Hidan, otherwise no dice.
-Blunt damage is not stopping him, no matter how hard she punches him as long as she cannot dismember him he'll be fine. She can break every bone in his body, won't have any effect.
-Byakugou is bypassed.
Soon as he gains her blood, he can go anywhere he wants, doesn't even have to engage in a fight any longer. Knowing her regen he stabs himself in the head and she shuts down.
Pretty simple outcome
bpd works = Tsunade wins
bpd doesn't work = Hidan wins.
Her greatest assets in battle are ignored, both her offense and her regen, so it's pretty much a given.
Btw can't help but notice S2 is pretty biased.
S1: If both have intel than Hidan knows what to do soon as he gains blood.
S3: If both don't have intel then she doesn't have byakugou activated (no reason to have it activated upon losing a drop of blood). Doesn't know how he's immortal doesn't know of the ritual, so it balances out.
SC2: Tailored to give Tsunade the win, clear advantage for her here, giving her full intel but him none.