The only two fighters I can see beating Pacquiao now are Mayweather and Marquez.
Mayweather-Pacquiao is an age old discussion that noone will ever know whos the better fighter.
Pacquiao-Marquez is a toss up. All 4 fights have been a toss up. The first three, either could have won. The 4th fight, one of them was about to be KO'd, and Pacquiao got the short straw on that one. It's always going to be a 50/50 fight with these two, they know eachother too well.
Damaged goods? Yes, but he would beat the hell out of most fighters still