No kisame was not weakened he seemed fine to me plus he was fighting kisame over the ocean kisames home friggin turn stop making excuses kisame was powerful but gai is obviously stronger.Rock lee is the one who cannot use anything but taijustu.
Gai can use ninjustu as well saying the fight was bogus because gai uses taijustu is like saying anyone who fights naruto is bound to lose since he is the main character.