iirc, xorr was destroyed by a super nova. that said, i'm sure both uatu/aron are more than capable of generating =/> energies. and even though starbreaker [being an evolved sun-eater] should be very uber, he lacks the feats for me to say he'd beat the watchers in a PIS free environment.
then again, watchers really don't have many high end feats either. meh, toss a coin.