this likely wont deter most opponents. also if you have room to have standoffs sticking out of the back of your robot, you’re not taking advantage of the space you have as much as you should be. to stop pushing from the back or front, you can simply apply a motor brake or hold to your drive motors, but for an all omni drive, preventing side to side shoving is more difficult. I had an idea to attach an omni wheel to the center of your chassis, like in an h drive configuration, but don’t power this wheel, in fact, don’t let it spin at all. make it fixed. that way, you’re robot can drive forward as usual, have a fixed turning point, and resist side to side pushing.