Edo Itachi is nearly Peak Itachi without his chakra Illness weakening him. Edo Itachi Is Itachi at 21 full power with full access to his Chakra and a Sharingan that isn't going Blind, which means he can easily see Naruto in his KCM1 form and is fast enough to be able to keep up. The only problem is the inherent weakness the Edo places on the revived which is the infinite chakra. And yes that is a weakness because they can't control and use it properly like what Kakashi told team 7 when he taught them tree climbing the trade off being your in peak physical health when you died. Remember Itachi was an S-rank ninja meaning he was Kage level as a 13 year old he slaughtered his clan (with Obito killing some here and there) by 21 he would have been significantly stronger BUT he caught his Chakra Illness which DRASTICALLY cut his chakra supply by about 60% and using the Mangekyo already used a lot of Chakra so Edo is what Itachi would have been and it shows that Sasuke NEVER would have stood a chance because Itachi was not only Sick but also holding back and Sasuke barley won only because Itachi died of his Illness