Emperor Joker is probably the best combat candidate, since he's likely to have leftover actions available. Baron Zemo and Nathaniel Richards could get some mileage out of it, too, but it's really meant for a back row leader figures like the Penguin or Professor X.
The thing is that the figure using the feat is only the one who stores up the tokens. Anyone on the force can use them. I would think you wouldn't want the guy with the feat up front because all your opponent has to do is Outwit Mastermind/Leadership and you lose all of your tokens. Also, since you can't boost damage it's not the crutch for underpowered characters that ICwO was. You want to have a leader figure store up tokens to enhance some big bruiser with high damage and weak AV one turn, then use it to snipe out to 13-15 range and try to catch your opponent napping on another.
In unrestricted V Silver Sable and E Taskmaster make interesting choices. Both have Stealth, Mastermind, and Leadership, making it very difficult for an opponent to cancel the tokens. neither of them has much need of the boosts themselves, so they are free to distribute them to their allies, and both are cheap enough to pack some great support. With Leadership, if you build a team designed for 3 actions a turn, you can bank the extra action whenever you get it. It would also be handy any time you are building well under 1 figure/100 points as those extra actions would otherwise be wasted.
In unrestricted, Prof X (U FF4 set) may be a great candidate as well. The sit back and enjoy kind of type. Realy fits the card 'fluff' too. With his rather large point cost (99) you're most likely to have left over actions as well.
In an unrestricted game, Vet Sidewinder from Ultimates.
-4 clix of Leadership
-Combat Reflexes to avoid a hit
-Serpent Society, so he can teleport his full move incase he gets in trouble.
-14 movement is hard to catch.