Kakashi easily dodges Killer B and cuts him in half with Raiden. He has more than enough speed and reflexes, and Raiton piercing/cutting attack power to do that.
Sc2
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Kakashi easily dodges Killer B and cuts him in half with Raiden; or he just warps him without him unable to even try to do anything. If B immediately goes Full Hachibi, Kakashi still trashes him with the Mangekyo Sharingan. His long range Kamui warp is much faster than B's Bijuu Dama. Kakashi (after finishing all his personal chakra) with a Kurama chakra supply (that was said to have increased 3x the power of his jutsu) could warp the Hachibi in the Kamui dimension and then re-warp it in the real world, and then finished all the chakra he received. Taking on account that Kakashi used also some chakra right before to travel between the Kamui world and the real world, I'd say it is pretty much clear and logical that without any chakra supply but only with his own chakra he can warp a mass that is slightly bigger than 1/3 of the Hachibi. So also Kamui GG his head or any Bijuu's head with relative ease, with the fast execution shown against the Gedo Mazo: Kakashi warped away a giant arm of the Gedo Mazo while Madara is already summoning it away with instant space-time summoning jutsu (Minato, of all people, couldn't do anything in that situation than ask Kakashi taking care of it, Minato, of all people, couldn't even perceive what happened when Kakashi used Kamui on the Gedo Mazo, he couldn't follow the speed of the warp, and had to ask him if he managed to kill it in time). Madara praised the feat and Kakashi's worthy as a doujutsu user.
Kakashi wins due to full intel, since an already-tired Sasuke could dodge his fastest v1 attack. Location might have a pretty big significance here though.
