I personally think Kakashi is slightly overrated.
He can probably beat Konan, if she comes down and stops being paper.
He can probably beat Hidan, if he has any information. If not Kakashi wouldn't be prepared for an immortal opponent, and he would get cut. His taijutsu skills were even with Hidan's as neither one of them was able to land a blow, and that is a manga fact.
He can pull a draw against Deidara, but no better than that because Deidara hates sharingan users and has shown that he is willing to sacrifice himself to kill them.
I don't think he can beat Sasori at all, but some people think he can. I don't want to get into it, so let's call it a toss up.
Kakuzu has too much chakra and too many lives for Kakashi to beat him on his own. The only reason that Kakashi got that first heart was due to Shikamaru and his team distracting Kakuzu.
The rest can't be beaten by Kakashi.
Itachi
Nagato
Tobi
Orochimaru
Kisame
and Zetsu are out of Kakashi's league.
You may ask why Zetsu, well if anyone wants Zetsu's feats I will give them to you.
Black Zetsu is currently fighting the Mizukage and her guards by himself, and white Zetsu beat the Mizukage and her guards during the Kage arc.
White Zetsu can steal chakra and copy people exactly, and can use mokuton apparently, and we don't know about Black Zetsu but if each half of Zetsu can fight the Mizukage and her guards then Kakashi can't win against both halves.