Can he use KA?
A healthy Nagato, most likely.
Edo Itachi doesn't have KA.
He does if he used it against Kabuto. I know certain conditions are set but if OP always him to use his arsenal outside of the canon rule (manga) then KA would be a problem.
But it's Edo Itachi. Not "Edo Itachi, but with every ability from every version of Itachi". KA was used on Edo Itachi, and when he had possession of Shisui's eye (for the brief minute or two during his Edo Lifetime) it was unable to use KA. So, unless the OP specifies otherwise, he doesn't.
Wow okay it was Edo Itachi that used KA in the first place but okay cool...
On Topic: Anyways OP if Ka is not restricted to the demands in the manga then he beats everybody. If not then Edo Itachi will be eligible enough to use Perfect Susano'o with his powerful Tsukyomi. So I assume that he would be able to beat 8 gates Gai.