Tsunade wins low difficulty.
Asuma couldn't slice apart Hidan's head until Hidan stopped moving and stood still in his ritual circle which allowed Shikamaru to paralyse him. Tsunade isn't going to stand in some silly circle allowing herself to be bound by Shikamaru's shadows. Asuma's katon and fuuton are effortlessly tanked and if he tries to close the distance to behead Tsunade with his chakra blades, Tsunade could simply punch him once to kill him. BTW, landing one punch is much easier than lopping off someone's head, so it should be obvious that Tsunade wins in a CQC exchange.
Katsuyu as well as its minis can also be used to overwhelm Shikamaru and Asuma who don't have a way of putting the giant slug down. They'll also constantly have to worry about Katsuyu's acid while having to deal with Tsunade herself. Tsunade is one of the few people that has the strength to break out of shadow possession and can tank shadow stitching via cellular regeneration.
All in all, Tsunade wins because, Hidan, who was equal in speed managed to outmanoeuvre Shikamaru and Asuma at the same time. He only lost his head once he became paralysed due to shadow possession which only happened because his curse ritual required him to stand still in a circle and stab himself. Moreover, even if Shikamaru's shadows manage to bind Tsunade, she'll immediately break out due to her immense strength so Asuma won't be able to finish her off quick enough. She also possesses far more chakra than Shikamaru and Asuma.
