Man this kakashi annying these days - but he wins isnt it obvious?
P.S. kakashi fanboys now lives in golden age just try ovoid such threads like this because every sec is creating threads about him with theories how he surpassed everyone.
Tsunade has never been noted for her speed (Slug princess lol) while Kakashi has always been considered to be pretty fast, and with the visual increase granted by the Sharingan, I honestly think Tsunade wouldn't be able to land a hit, while she'd also have trouble defending against Kakashi's attacks.
Kamui obviously also helps him a lot
Katsyuu might however be a problem for Kakashi, since I don't think he'll be able to take care of her, at least not without tiring himself out a bunch.
So this could really go either way really
EDIT: Forgot to mention, if Tsunade lands a punch, it's definitely over for Kakashi. :p
Decided to make half of a fanfiction for this battle (sorry for not taking the environment into account much)>_>
Kakashi automatically removes the head band to reveal his Sharingan, knowing full well that underestimating the Hokage would not end well for him. Kakashi tests the playing field by throwing a handful of shuriken in her direction, immediately forming hand seals afterwards. Tsunade casually dodges them - it's a small feat for one trained in evasion. During this time, Kakashi had already formed his Raikiri and sped straight in Tsunade's direction. Close quarter combats may not be the greatest idea against a taijutsu based shinobi like Tsunade, but he had faith in his Sharingan's precognition. Aware of the danger that the Sharingan and a jutsu of that level possessed, Tsunade decides not to take any risks. Using a simple punch aimed at the ground, the earth rumbled beneath Kakashi's feet. Rocks flied everywhere, and Kakashi jumped in confusion to avoid the mess. Tsunade at this time used her chakra control to discreetly hatch onto a flying rock heading in her opponent's direction. Only when in perfect striking distance did she reveal herself to Kakashi, and use her impressive chakra control to launch at him with amazing speed and smash a hole into his chest.
...But this was all in Kakashi's calculations. Tsunade gasped as the "Kakashi" she smashed suddenly turned into a spasm of lightning and enveloped her body. She tried to move her hand, but it was more trouble then it was worth, for she was completely paralyzed. The real Kakashi soon appeared from the shadows, carrying another Raikiri with his intentions clear. He went to finish off his prey, but the slug princess was not yet out of tricks. While not being a ninjutsu type, she did have basic control over her lightning style. Chakra nature 101 -> lightning is known to diffuse other lightning. With the help of chakra control similar to a Hyuuga and knowledge of human anatomy, Tsunade sends an electrical surge throughout her body to rid herself of the paralysis by a small extent. This extent was apparently enough, for when Kakashi was just meters in front of her striking her chest, he was surprised to find out that his jutsu had missed its mark by an inch. Tsunade had diverted the attack by a narrow margin. Instantly realizing the situation, Kakashi had enough smarts to retreat right before Tsunade regained her strength and attacked with a tree breaking punch; her power missing its target and destroying the ground where Kakashi was shortly before. Normally, the damage caused would have been enough to severely debilitate a ninja to the point where combat was nigh impossible. Even great medical ninja would need time and equipment to heal such damage. But Tsunade was the best of the best. Using the Byakugo, the hole had stitched itself to normal.. in almost no time at all. Confidence beaming through Tsunade and slowly draining from Kakashi, she summons her personal set of medical ninja tools and prepares for round 2.
Truthfully Kakashi does seem to have a good way of bisecting Tsunade. She would probably have to summon Katsuyu to have a fair chance. Kamui is also a powerful tool to have (Kakashi's most powerful weapon by far IMO)