- "Now when you think of Sumo, you think of the honour, the tradition, the slapping of talcum powder onto Oriental backsides. But this Sumo isn't about overgrown men wearing nappies. It's about nothing plump, rotund or portly. It's about lean, mean fighting machines trying to bash each other's brains in!"
- — Craig Charles introduces Sumo in Series 2, Heat F
Sumo was one of the Trial events that featured during the first two series of Robot Wars. It was one of only two Trial events to feature in both series, the other being Football, and was designed to test a competing robot's strength and pushing power. Each robot would take turns to battle with one of the House Robots on a small circular platform surrounded by tyres (the 'ring'), aiming to either push the House Robot off the ring or remain on it for a full 60 seconds. The robot which survived for the shortest amount of time was eliminated from the competition. In Series 1, the robots competed against Shunt; in Series 2, they either faced Shunt or Dead Metal.
- Robot Wars: The First Wars/Heat A
- Robot Wars: The Second Wars/Heat F
- Robot Wars: The Second Wars/Heat L
Sumo returned as a side competition in Series 4, now known as Sumo Basho. It was also planned to be a side competition in Series 3, but a behind-the-scenes accident caused it to be cancelled along with several other events.