Honestly the stupidity of some people ~_~. Of course Gai wins in an all out fight. Gai has the Gates which increase his speed way above Kakashi's, he [Kakashi] can't focus on him for Kamui because Gai is too fast. Yes Kakashi has used the Gates but ONLY the first which doesn't really increase speed it unlocks the brain.
For those of you saying Gai is faster yet Kakashi is stronger well then in terms of physical strength that means nothing (and I'm pretty sure Gai is stronger than Kakashi) as like Kakashi said something along the lines of: All her strength counts for nothing when she can't land that single punch - When fightning Sakura.
In terms of Ninjutsu, sure Kakashi could use replacement techniques but he has to see the attack coming before he can actually counter it.
With Genjutsu with all that chakra flowing around I'm unsure as to if Genjutsu would even work when the gates are opened, also most Sharingan genjutsu require eyecontact which of course because of Gai's speed wouldn't be able to effectively use one.
Also in terms of the Sharingan even though it increases reaction speed, even if his mind can keep up with it his body won't be able to. Its like if a fat man had Sharingan sure he might be able to see it coming but his body wouldn't be able to react in time.
Btw to you guys who say "Oh why didnt Gai get chosen for Hokage instead of Kakashi" well i'll ask you this, why didn't Naruto get chosen for Hokage? The village loved him and he had shown that he was indeed one of the most powerful shinobi in the village (completely outclassing Kakashi who only lived because of Naruto's help).
Also intelligence isn't everything, most people need time to think. People who rely on instinct and reflexes don't need time, once again it comes down to Gai being too fast for Kakashi to react.
I know this won't change the Fanboy view but meh.
