From the Super Mario Wiki
Sir Hop-A-Lot is an enemy in the game Wario: Master of Disguise. It appears in Carpaccio's Lab and later in Allergia Gardens during Wario's adventure there. It appears to be a green colored Sir Lance-A-Lot that uses pogo-sticks as both transportation and as a weapon. It also has the ability to press down switches and mushrooms depending on its location. If Wario damages it enough, it will lose its pogo stick and act like a Sir Lance-A-Lot.
This crazy robot patrols around on a huge pogo stick. It's got the hops, but maneuverability is a bit of an issue.