REVISED TACTICS:

Okay, both of our robots are invertible. That's fair. The downside for me is that I don't have an active weapon, which is okay. The upsides for me are tougher armor, 0 ground clearance at front and back due to my scoops, and better pushing ability. I will not give him a chance to get under either the sides, and will keep the front or back towards him at all times. I will still try to exploit the side and rear ground clearance, and use my pushing ability to ram him around and into the pit. Once again...

If I feel that I can't push him in without suffering major damage/being pitted myself, I'll shove him into one of the house robots. Only after I feel he's been worn down to near-immobilization will I pit him.
Reposting so you don't forget.