Kakashi wins mid-low difficulty. Mifune has great speed and reactions but he is strictly a CQC fighter whereas Kakashi has great speed and reactions himself and 3T precog to top it off. Raiton streaming at close range as well as bunshin tactics get the better of Mifune.
Kakashi mid-low difficulty. Darui is another one with great speed and good reactions but he gets outclassed in CQC. Kakashi is on another level when it comes to that.
Kakashi low difficulty. Yamato is pretty versatile but his physical stats and CQC ability are far below War Arc Kakashi's.
Kakashi mid/high difficulty. Iron Sand is never going to hit someone of Kakashi's speed, let alone Hiruko's attacks. Suiton and Raiton Wolf can catch Sasori if he tries levitating himself. On the ground, he more or less gets outclassed.
Kakashi wins mid/high difficulty. The difficulty arises from his inability to actually catch Deidara in the air but his deadlier bombs are easily countered by raiton flow through ninja tools, while he can avoid C1 easily as Hebi Sasuke did.
Orochimaru (Healthy, w/ hands)
Orochimaru wins high difficulty. Kakashi just doesn't have the means to outright kill him while Oro does have the physical stats to react to his speed, while not being too shabby in that category himself. Multiple boss snakes, 10,000 snakes, and Oro's true form should do the trick.
Kakashi wins high difficulty. The difficulty arise from having expend his reserves to kill Kakuzu so many times in different ways. Those attacks of his are easily reacted to, countered/ evaded, and perhaps even copied. Riaton >> Domu and those threads that the monsters are made of. Bunshin feints and genjutsu should come in handy here as well.
Kakashi mid difficulty. I sound like a broken record but **** it. Genjutsu is a non factor. No significant gap in speed and reactions between the two. Stalemate in CQC. Kakashi's ninjutsu takes a nice dump on Itachi's. Bunshin feints, raiton streaming, and possibly the first gate give him the edge.
Kakashi mid/high difficulty. None of those summons are landing a hit on him and can be dispatched by Raiden and raikiri infused ninja tools. I suppose that the Cerebrus could be a problem though.
Darui, without intel, cornered these clowns by himself before Kinkaku went apeshit. Why do they get overrated so much? Probably because of that cheap sneak attack on Tobirama and the Second Raikage.