Tyranitar seems better to add to a team that needs him to do something specific, rather than build a team around him from the start because, like you said, there are a million ways to use this guy. DDance is extremely dubious being weak to Scizor Bullet Punch, Azumarill Aqua Jet and anything with Mach Punch. That's really unfortunate. He seems to be best utilized as a pivot rather than something that's intended to stay in for long bouts. He can EV'd to take the hits you need and threaten with really strong moves and set up sand if something else needs it. Choice sets (Band or Scarf) are good for these reasons, and one of the numerous resistance berries can be really helpful to use him as, say, a Scizor lure that you can KO with Fire Blast, which is also great against Ferrothorn. Assault Vest has also been very useful taking some amazing hits from the likes of Rotom-W for instance. He's susceptible to all forms of status however, so something that can absorb obvious burns and Thunderwaves is much appreciated.