Once it sets up, yes, you can't switch in many mons without getting 2HKOed (one unlucky quote from my side).Such as who? +2 Flash Cannon removes pretty much all of them bar Unaware Clefable.
On the other hand - every choice scarfed fairy, like Togekiss or Gardevoir, can take it out.
I don't say it's bad. I really love the tripple headed dragon and it got some love with NP.
I'm just saying I don't see it ending up in UBER, with Zacian, Zamazenta, Marshadow, Zeraora, Three Musketeers and other hard-hitting, fast mons in the game.
But I could be wrong, tho.
I would like to have it in OU, at least for a while, because I'm not that much a fan of UBERs in general. ^^"