The most powerful people are off in other worlds, or have been disposed of by Palpatine (ie, Yoda, Obi-Wan, Mace, Kit Fisto, Saesee, Agen Kolar, Ki-Adi, Aayla, etc etc). Plus, he does have the Clones with him, which takes care of ganging up on a few Masters...also, if you think that the wars are going on, there has to be a certain percentage there that are either semi-retired Jedi (sounds lame but you know what I mean), younglings, people like Jocasta Nu who aren't fighters, and inexperienced Padawans. Anakin himself is skillful enough to be awarded the rank of Master, even though they don't do it, and he is even more powerful when he turns to the dark side, so he could take out anyone in the film just about, save for Obi-Wan (which we might say he could've, he might lose by something stupid), Palpatine he's destined to kill so if he fought him he'd win, and Yoda would put up a fight. When you put it that way, Mace Windu, 2nd on the council, BASICALLY 3rd best Jedi in the whole realm, if Anakin can beat him, why can't he beat anyone lesser?