Although not a robot from this year the most powerful shot I have ever seen was 159's robot from 2014. It was a catapult and the power it had was incredible overkill. The catapult was powered by four 500lb springs. 2000lbs of force! 2000!
It had so much power that one time it was triggered without a ball in the 'pult and the bot launched up into the air and nearly did a complete front flip. The best part about it is it scared the safety inspectors to death, so in order to pass inspection the inspector told us if a team member stuck their hand in the springs when they were extended and held their hand there for 5 seconds we would pass inspection. So a guy from our team volunteered and promptly put his hand in the spring. A spring that, if its mounts failed would slam closed and crush his fingers into oblivion. This robot still scares 159ers to this day, its power was legitimately terrifying.