So lets say he went through a wormhole that sent perfect clones of him back to the Jedi Civil War, Darth Bane era and The Old Republic era. To prevent age from being a factor each clone is in his prime, but the force abilities and lightsaber techniques remain the same. So how would he do against the Jedi and Sith? In his era he's considered one of the best swordsmen in the Jedi Order in his era so I'm wondering how he would do in other eras.

To me he would do OK, but I think he would be at the same level of a Jedi Knight and the Sith equal at most above average. The reason why I'm saying that is because his era they are at peace. There's no real Sith threat that he has to worry about fighting. In those eras on the other hand there were actual force users with lightsabers you risk the chance of fighting which also had wars. Sure Windu's techniques are good, but he still wasn't training to use them on a real threat. Over the years of peace that's going to affect the training being passed down from one to another. When he goes up against a master he's going to get r­aped because they were trained during an era of war so they have to be strong.

doesn't matter; not canon

They said all the good shit wasn't canon?

Damn it people stop being smart asses.

All the media liked to say that each era's jedi and sith were less powerful than the previous, so, there is that.

Then there's also the EU not being canon.

Zez Kai ell would kick windus ass in a lightsaber battle