Shanoa's another non-Belmont. She only beat Dracula because she could reflect his own power back at him, though, essentially rules-lawyering him to death. Now, you COULD argue that anybody who can take down Soma and isn't Julius counts as a non-Belmont, though Soma really isn't as impressive as Dracula was. At least he's better than the other candidates.
Heh, imagine if the games starred Dario instead.
I was always under the assumption that anybody COULD defeat Dracula, but the possibility was pretty low for a non-Belmont. The Belmonts are trained specifcally to take him down, but it's not like Eric LeCarde would have been completely incapable, even if Dracula just sat there and tried to take it. The non-belmonts can clearly do something, or you'd never get the chance to play as them. It's just a much bigger feat if somebody not from the Bloodline manages it - Nathan defeating Drac doesn't make Dracula look weak, it makes Nathan look stronger.