At this stage in the game, most of the UFC champions are dominating their divisions. Most of the champs have proven that they are the best in the respective divisions by fending off their challengers.
Currently, the UFC champions are Dominick Cruz, Jose Aldo, Ben Henderson, Carlos Condit (in the interim), Anderson Silva, Jon Jones and Junior dos Santos. These men all have weaknesses that have yet to be exploited—but eventually can be by the right fighter.
Here is one flaw that each UFC champion has that can be exploited, plus the ideal fighter to knock off the champ.