Hi Lilmanmgf,
This Sumobot you are building, Is it going to have reverse and forward, or only forward and stop? I ask because if you want it to have reverse, then an H-Bridge is what you are looking for. If it only goes forward, you might do as well or better with a fast acting relay, and lose the heatsink, MOSFETs and some of the confusion, you would likely still need a small switching transistor and a snubber diode. I know these bots are pretty small, and the space and weight saved might be useful for something else.
JS