I think Mosely could benefit from sparring with Malignaggi as was already said, maybe Spinks or Edner Cherry. Chasing Judah or or decaying Sharmba mitchell wouldn't around the ring wouldn't be a bad idea for a few rounds if either one of them can go righty for a few.

For mayweather, its probably a lot more difficult stylistically to find someone that matches up shanes style overall. Finding someone who works aggressively behind the jab with enough speed might be difficult. Maybe Bradley if they wanted to go smaller and he would be good for counters.