Jermain fit the style that Manny teaches. Tall fighters, good jab, power in the right cross.

Hearns
McClellan
Lewis
Wladimir
McCall
etc

Rooney has a style good for short guys or guys with short arms and fast hands. I think these guys would be good for him:

Joe Mesi
Sultan Ibragimov
Lamon Brewster
Jeff Lacy
Ricky Hatton (not that he needs a change but his style is condusive to Rooney's training)
Miguel Cotto (same as above)

And so on