They could fuse all the destroyed Universes with Universe 7 making a giant Universe 7. If Universe 7 wins, Zeno can't destroy Universe 7 because they won and what goes into Universe 7 is up to them. It will also explain the huge influx of powerful planets shown in GT but not now (Even if I really don't want GT to be canon). How they can ask for both the revival of those Universes and join them with Universe 7 with only one wish is going to be tricky, but we'll see!

Yeah, calling it, the winner will use the Super Dragon Balls to wish back all the universes destroyed in the tournament. I can't see guys like Goku or Gohan turning a blind eye to the countless lives that would be lost in this tournament.