I am Kakashi's fanboy, but I never stated he can solo Hashirama via Kamui. U_U
Here is a list of current kage and Akatsuki that I think Kakashi can take on without Kamui:
-Gaara
-Tsunade
-Mei (maybe)
-Hidan
-Kakuzu
-Deidara
-Sasori (maybe)
Dw, it was to you directly, just in general, a lot of fanboys (of any character) rely on their strongest weapon as if its a game opener.
Kakashi without MS ? Well i would have to counter that list of yours:
Sasori ? Nah, i just made a recent thread on him why he equals MS Itachi (if not beats him) as well as far surpassing 3 Tomoe Itachi.
Deidara ? Yeah, this is highly possible, but the range seems unfair on Kakashi's part.
Hidan ? Kakashi wins by far
Mei ? I would still give this to Kakashi
Tsunade, is problematic for Kakashi, i don't think she should be underrated.
Kakuzu ? He would be overwhelmed on most counts, Kakashi wouldn't have the opportunity to destroy the masks due to Kakuzu supporting them (in his fight, he was spread thin on the foes he had to face).
I could give you a detailed argument on why Kakuzu and Sasori surpass Kakashi without Kamui, but i'll have to leave it for now.
On a Final note, he wouldn't get past Gaara's Sand Defense. I'm not too sure on how this battle would work out.