When a match ends all of a robots motors shut off, Which means your clamping mechanism that ypure using to climb has to use pneumatics, or will they stop the motors from shutting off?
You can always incorporate some sort of hanging lock or passive ratchet into the hanging system to take power off of the motors.
Rubber bands? There are lots of ways to counter the fact that motors go to coast. It is just an engineering problem and there are many ways to fix it.