These instructions describe how to build a sumo robot with a color sensor for detecting the line and two bumpers with individual touch sensors. These instructions require only parts found in the standard EV3 education core set.
Build a second motor assembly as a mirror image of the first.
Build a second front bumper as a mirror image of the first.
Build a second touch sensor module as a mirror image of the first.
Connect the left touch sensor to port 1 and the right touch sensor to port 2. Note that the wires cross underneath the EV3 brick.
Connect the left motor to port C and the right motor to port B.
You have completed your EV3 sumo robot.