Nova
snitches get stitches
Tyranitar was a great Pokemon in BW1 with his massive stats and great movepool. He had the ability to surprise some of his usualy checks such as Ferrothorn, Skarmory, and Scizor with Fire Blast and Gliscor with Ice Beam. There were multiple sets he could run including Specially Defensive, Scarf, Band, and an uncommon but very threatening Dragon Dance set that could clean up late game. In BW2, however, I feel that Tyranitar is not as effectve due to all the fighting types running around and the vast number of Rain teams as well as Sun teams running Venasaur and Dugtrio. Personally, I prefer Hippowdon over Tyranitar as a Sandstorm summoner because he can check some of the top threats in the current metagame such as Garchomp, Terrakion, and Scizor. Hippowdon also has an easier time winning the weather war due to having recovery through Slack Off