first of all, i have never built a mini sumo bot, i don't know the all the rules, and this is just an idea i got from watching mini sumo robot films (yes i have very little to do).
after watching many sumo films i think i found out what makes most people loose (if they don't screw something up and just go over the edge themselves), they cant get away when the opponent pushes them.
so i found two ways of getting away from an opponent thats pushing you:
A) a teleporter that teleports you away from the opponent.
B) you make your robot round and mount tank threads around so when an opponent pushes you, the treads start to move, and either you or your opponent moves.
since the only person i know of that has a teleporter is Willy wonka from charlie and the chocolate factory, so i think the best way to go is with the treads.
i made a drawing with a highly advanced program.
and then, you would mount the all seeing eye ( http://www.imakeprojects.com/projects/seeing-eye-mouse/
) so when the eye see that your not going the way you want, the threads start to move and zapp your out of trouble, for now.
you would have to make some sort of cleaver mechanism for the threads, but it should work.
and check out www.imakeprojects.com
, its lots of cool stuff there.
if this was a stupid idea or if its against the rules, please tell me so i can delete the post and spare myself from humiliation.