Ok before i get rape by kakashi fans (not going to say any names) but he will be almost useless in this fight. Unless Gai and Kakashi were to fight first then whoever won that then helps the teammate. B was on equal ground with Kisame throughout the last fight until Sameheda betrayed Kisame (plus B was focus on saving his friends), Gai vs Kisame (I'm going more towards Gai just because of the gates even though to me Kisame wasn't taking him as seriously maybe its his personality. Gai vs Kakashi (they said they were about even BUT totally different fighters;Gai (strength,speed,tatjustu, unknown ninjustu, and gates) Kakashi (Speed, 1 gate, little speed and strength (Not saying his slow, but his not faster than gai), 1,000 Justus (Yeah, ima throw that in there since most will likely say "But he has 1,000 justus, he automatically rapes." We have not seen more than 10 different justus from kakashi..) Ms (Kumui, TRANSPORT justu), sharingan. So since manga said they were even anyway its a toss up. Kakashi vs B....really?