Ouma has a great chin, good endurance, and a nice relentless style of his own. Add to that he's just as big as Margarito and will make Margarito work.
I'm going with Ouma too ... he's been robbed 2 straight times but I think his style gives Margarito problems.
Ouma is so washed up it would be a mismatch. I know Ouma was robbed but he still looked like **** against two journeymen recently. If Rubio had better stamina and workrate he probably would've koed Ouma, and that was some time ag. I think Ouma takes this pretty convincgly a few years ago, but now he wouldn't be able to hang with Tony's power and pressure.
I wasn't sure if Fitz meant a prime Ouma, or the current Ouma since he did mention he'd give Marg hell despite being robbed twice. I'd probably favor a prime Ouma over this current Margarito.