Unfortunately Danny_G, Ricky Hatton was not in the top 10 p4p fighters as of the most recent poll held by Saddoboxing, so he was not considered.

And thanks to Greg aka Killersheep, here are the stats on who has won titles in different weight divisions...:

Titles won in different weight classes (Big 4 only)

Mayweather - 5
Pacquiao - 4
Mosley - 3
Cotto - 2
Juan Manuel Marquez - 2
Rafa Marquez - 2
Winky Wright - 2
Hopkins - 1
Taylor - 1
Calzaghe - 1