Could defeat:
-Hidan. Even if Kakashi didn't know Hidan's abilities he would never let himself get hit. After the first Chidori at the heart Kakashi will realize Hidan can't die and fight accordingly.
-Konan. What has Konan done to convince you that she can defeat Kakashi? Her 600 billion explosives? Well I'm sorry, but that isn't a technique she can use on the fly. She had to prepare for that fight against Madara.
Might be able to defeat:
-Sasori. If I was an idiot I'd blurt out that Kakashi would win..., but no. Kakashi is fast but you have to realize that a single cut, even a scrape, from any of Sasori's puppets would leave Kakashi paralyzed and dying. If that wasn't enough Sasori also has poison gas. Inhaling even minute traces would prove fatal. On the plus side, Kakashi does have the Sharingan which makes dodging the puppets a lot easier. But unless Kakashi knows of Sasori's killspot I wouldn't bet on him
-Kakuzu. This is perhaps thee most debated Kakashi fight I've seen on these forums recently. Kakashi can take out Kakuzu's Iron Skin easily, but that's only 1 out of 5 hearts. It's also a fact (and I mean fact) that Kakashi was being held back in that battle by having to protect Ino and Chouji. Had they not been there Kakashi wouldn't have had to use a double Chidori to counter Kakuzu's lightning attack. That alone depleted a hefty chunk of his chakra; chakra that could have been used strategically at fighting against Kakuzu. Does that mean Kakashi would have won? No. But it does mean he might have been able to take out at least another heart or two.
Could not defeat:
-Deidara. Kakashi is not a long-range fighter. Deidara would never, and I mean never, let himself get in range of Kakashi's Chidori. The only long range technique that Kakashi has is Kamui but he would never use it in a 1 versus 1 fight. That'd be tantamount to suicide.
-Kisame. Kakashi's greatest weakness is his limited chakra supply. Kisame has that comparable to a Bijuu. Not to mention Kisame has Samehada. We saw how quickly Samehada is able to devour chakra in his fight with Bee. Even with Kakashi's speed I doubt his Chidori would penetrate Kisame before Samehada absorbs it. A ninjutsu specialist is a terrible match-up for Kisame no matter how strong they are. To beat Kisame you need a taijutsu specialist.
-Itachi. Kakashi's fought him in the past but to no avail.
-Nagato. He speaks for himself
-Tobi. No.
aside from deidara this is pretty much it.
you are saying that deidara is long range fighter and kakashi only has ms.
but you are missing one point deidara fights with his clays he makes birds (and stuff) and makes them attack.
for someone like kakashi it's not a problem to dodge or trick them. (he has already done that)
deidara needs a strategy he'll either go for c3 or c4
sasuke was able to analyze and escape the c4 so I believe kakashi can also do that.
we don't know how devastating c3 is so I don't have anything to say
in short deidara might be a long range fighter but he cannot win against kakashi with some birds he needs to do something new before running out of chakra or clay.
and this would give kakashi enough time to come up with a strategy and defeat him
note: I'm not saying easy for kakashi. "kakashi barely wins"