Well first do you mean powerless as in normal human? If so Batman has to be the favorite 7/10. Thor has thousands of years in combat but coming down to a single fight lasting 5-30 minutes I am not sure that makes an advantage for Thor.. I know Ellis and DeFalco in particular rightly portrayed a powerless Thor as a dangerous foe. However he still had super strength and durability well above human normal. I think he had mjolnir as well. Bruce has fought and won against that class. That is 5/10 territory. Batman is considered peak everything and was actually depicted as at least low super human level in my opinion. I am just thankful Thor didn't draw Batman in the old JLA\Avengers fight. Bruce would have kicked Thor in the stomach causing him to inhale knock out gas. That sounds ludicrous but you never know how far D.C. will go to protect Wayne.
Fair enough - but i think Bruce would defeat Thor if both were at human class stats.
I also think that the full powered Shazam level is a peer of classic Thor power levels.
So i think Bruce with Shazam powers would not lose to Thor. It would be fun to see if written right