In last years competition, team 1771 used an extremely effective robot with a funnel and a fan at the end used to create a vacuum to pick up the game element. I've heard that they used two Fisher Price motors and a timing belt to achieve the fan's movement. I've also heard that it gave them 350 pounds of vacuum force, if you could apply that to your robot, you would be able to increase the normal force from 120 pounds to probably around 420 pounds under best conditions possible. Though, that's being very kind to the suction.
That said, this idea is still is testing, our team might try working on a prototype just to see if it is possible, but if it is, I don't see why judges would disqualify us. The fan would still be bulky, and suck up a large amount of our battery life, two possibly life killing consequences.
Heres a link to 1771's impressive robot on youtube.
http://www.youtube.com/watch?v=QeQSGmFnKAE