Thew way I see it, It's only real niche in current Ubers is Baton Passing.
With the new 5th Gen. stuff, I don't think it's likely to pull that off even in OU any better that Gliscor or Smeargle.
As for it's bottomless, and unredictable move pool, it's no more unpredictable than Smeargle or Jirachi, and once it uses a move, the jig's pretty much up for it.