Who do you think is the worst or most frustrating boss in the series?
Personally I'd have to go with King Bob-omb from Paper Jam. The timer gimmick is really annoying at first (It was one of the only two bosses in the game I died to) but once you figure out that one bomb counter it's absurdly pathetic. A neat idea that just felt half-baked, which honestly sums up Paper Jam as a whole.