Im not arguing that dragon dance is superior, it definently is, however I wasnt sure if a curse tyranitar was viable, since it sill has a great HP and special defense stat. From the looks of things its wont be particularly easy to set up with him, but im going to have to give it a shot, just to see for myself. I want to see how well it does. If it gets eaten then so be it, it was in the other options section for a reason, lol. As far as regirock goes, is he used commonly? I fought one once, and it surprised the pants off me with counter and ohkoed whatever it was I tried to hit him with.
Regirock is definitely not used commonly. That doesn't mean it's bad, but it's just not as good as the commonly used mons. There are a lot of Pokemon that are still viable, but aren't used very much, due to being too niche, or being outclassed by someone else.