If they need to use the perimeter wall at all, how would they fit in the 18" sizing box without touching the sides? There is, after all, a rule prohibiting robots from using the sides of the sizing box to hold their robot within regulation size.
thank you for pointing this out. i know which robots are in question here and i remember thinking about this the first time i saw them compete.
Bottom Line = Not legal, if it truly requires the wall.
Opponents could make a polite request for an inspection (as early as is possible before a match so that the robot could be made legal in time to compete), and the refs would have to declare the robot illegal if it required outside help (the wall) to stay inside the 18" size constraint.
I was told by Rick F. that the robot in question had a pin that held their catapult up and that it was indeed NOT resting on the wall. I can only assume that this is correct as he was at said event.