[GeeTwo]

I only see two wheels. Is there a caster under the battery, or perhaps two flanking it?

This appears to be similar to our Ultimate Ascent drive train, which featured two driven wheels at the front corners, and two idle omnis at the rear corners. Interestingly, we found that it drove across the field far more effectively in reverse than in what we had designated as forward. I suspect that this is because the effective CoG of a roughly cubical robot shifts away from the direction of acceleration. With your currently low CoG, you may not see this effect.