Would Succeed: Kurt Angle

Kurt Angle is possibly the most elite athlete to ever step into the wrestling ring. No one else can claim Olympic gold medal caliber ability.
Though he's aged out of full time MMA competition, Angle would be an ideal 'dream match' opponent for men like Randy Couture or Rich Franklin, whose MMA careers are over but could draw huge numbers on a special attraction fight.
Kurt's real life combat sport experience would be invaluable in MMA. His ground game is obviously solid; He once beat a man nearly a hundred pounds heavier--Brock Lesnar--in shoot amateur wrestling match, with a surgically repaired neck. Angle would have been dominant in MMA had he made that his career choice, but he could still be a top draw just based on his reputation alone, and his fighting skills would keep him from being embarrassed like CM Punk.