From the Wikipedia page on Robot Sumo:
Robot-sumo, or pepe-sumo, is a sport in which two robots attempt to push each other out of a circle (in a similar fashion to the sport of sumo ). The robots used in this competition are called sumobots.[1]

Robot-sumo

The engineering challenges are for the robot to find its opponent (usually accomplished with infrared or ultra-sonic sensors ) and to push it out of the flat arena . A robot should also avoid leaving the arena, usually by means of a sensor that detects the edge.

The most common "weapon" used in a sumobot competition is an angled blade at the front of the robot, usually tilted at about a 45-degree angle towards the back of the robot. This blade has an adjustable height for different tactics.

Robot-sumo is divided into classes, fought on progressively smaller arenas:

  • Heavy-weight. Standard in the National Robotics Challenge . Robots may weigh up to 125 pounds (56.8 kg) and fit in a 2-foot cube (61 cm).
  • Light-weight. Also standard in the National Robotics Challenge . Robots may weigh up to 50 pounds (22.7 kg) and fit in a 2-foot cube (61 cm).
  • Standard class (sometimes named Mega-sumo) robots may mass up to 3 kg and fit inside a 20 cm by 20 cm box, any height.
  • Mini-sumo. Up to 500 g mass, 10 cm by 10 cm, any height.
  • Micro-sumo. Up to 100 g mass, must fit in a 5 cm cube.
  • Nano-sumo. Must fit in a 2.5 cm cube.
  • Pico-sumo. Must fit in 1.25 cm cube.
  • Femto-sumo. Must fit inside a 1 cm cube.