Honestly it depends on how you would think the battle would win. If Kakashi successfuly used Kamui from his Mangekyo Sharingan it would be an instant win. However if it was a battle of pure Taijutsu Tsunade would have an easy win. Also you have to keep in mind Tsunade is a former Sanin and current hokage while Kakashi was a candiate for Hokage. Another thing to keep in mind is Tsunade and Kakashi's families. Kakashi is the son of the white fang(Sakumo Hatake) while Tsunade is the descendant of the first Hokage which could influence her healing abilities like it did in the battle against the true Madara Uchia(sorry if I spoiled it). Now keep in mind Tsunade was able to survive being impaled through her chest and regenerated it. Truthfully I'd have to give Tsunade the advantage in Taijutsu, Stamina, and Endurance, but I'd give Kakashi the advantage in Ninjutsu, Genjutsu, and Strategy. And one last thing to remember is who their senseis were: Tsunade-Sarutobi(the third hokage). Kakashi- Minato(The fourth Hokage). Tsunade wins this because she is the hokage which means that she is the strongest ninja in the hidden leaf village, and on the other hand kakashi is just a jonin.