Joker was a Sumo competitor from Techno Games 2003. It was a stand in that was used in the Sumo after spending almost a entire day not being needed. It lost its only match due to not having the right attachment for Sumo. Joker has resurfaced under the name Shockwave and has started competing in the 2015 Robot Wars events.
It lost to Storm Chaser after the intended blade for Sumo was not at hand so Joker went in with the Football scoop resulting in Joker doing a wheelie and getting pushed off in 18 seconds.