Would Succeed: Ernest "the Cat" Miller

When you're a two time world kickboxing champion, you can definitely hold your own in a legitimate fight. Ernest Miller may not have been a tremendous wrestler, but his entertaining antics and personality won over legions of fans.
Eric Bischoff's personal Karate instructor was asked to join WCW to try and enhance its Mortal-Kombatesque unnamed masked wrestlers division. Glacier was the first, and then Mortis and Wrath were developed to give the 'hero' someone to fight. But Glacier needed backup, and they picked Ernest Miller.
Mostly remembered as a comedy act or a joke, Ernest Miller would be a good candidate for the MMA cage. His striking would already be among the best in the world, and if he developed a ground game he would be great for an exhibition fight, even at his advanced age.