I know the Bristol Bot Builders guys used a Beetleweight in a "Beat the Boss" event (I think that is what it is called) in which all the AWs faced off against the BW.



(42:50 on the video)

Perhaps a smaller BW could serve as a house robot but to be honest, AWs are perfectly capable of making enough danger/entertainment all on their own.

Hazards are a cool idea too, trying to work out the neatest way to make a dropping pit with release button...
If it was functional as a button, I can see it breaking really easily, especially against a AW spinner. Personally, I can't see why someone can't just watch the match and then when a robot hits the "button", that person pulls on a string which releases a catch and a pit swings down open like a trapdoor.