This goes without saying. I'm glad that Oda appointed a Shichibukai whose ability to threaten others isn't due to his own strength, even if it is for comic relief. Buggy aside, I'd struggle between Law and Moriah--I'm not sure that Law is strong enough to defeat Moriah on his own in a straight on fight, since he'd need to use tricks to get around it. But if Moriah has time to prepare and had access to any number of powerful shadows, Law would definitely be screwed.

I don't care how thoroughly he's trained, Buggy is all talk and no substance.

Buggy. Moriah is pretty weak, too, and only powerful if he invests FAR too much time to become that way.