I am going to make an unorthodox suggestion:
Tyranitar for S-Rank
I think by and large Tyranitar is an S-Rank Pokemon. At the beginning of BW2 I would be inclined to disagree, but in the state of the current metagame I think Tyranitar deserves its rightful place in S-tier. First of all, the utility of Sandstream has been massively downplayed by most people. Sandstream has been adopted by OU as the way to disrupt Sun and Rain without disrupting too much on your team. Really, Sand teams aren't necessarily teams abusing Sand, but weatherless teams "abusing Tyranitar."
TTar's versatility and excellence in its varied roles only makes it easier to adopt into teams. Let's take a look at its sets for a moment:
Choice Band: Choice Band Tyranitar is the defining set of the metagame right now. That sexy 604 Atk STAB Pursuit enables some of the OU metagames top threats to really shine. Particularly Keldeo and Landorus-I, two S-rank offensive threats, become almost unstoppable monsters after Ttar has successfully trapped their respective checks. Choice Band Tyranitar Pursuit is so powerful it can be used to trap stuff that is not weak to Dark attacks like unsuspecting Choiced Politoed's and (some) Ninetales (eliminating the opponent's weather from the match). IMO it is the best trapper in the OU tier right now (that's right Gothitelle can suck it, I hate that POS).
Choice Band Tyranitar is not limited to trapping though. Stone Edge can act as a powerful wall-breaking tool. CB Tyranitar also retain enough bulk to check special threats, combining the best of its offense and defense. Really CB Tyranitar is the best way to play Tyranitar, a weather inducer. Get in, cause the most amount of damage as possible in a very small period of time, get out and be safe to come out to reset weather latter.
Specially Defensive/Support: SpD Tyranitar is a critical stopping block to the majority of the tier's special attackers. In one Pokemon you can carry weather support, SR, and trapping support. With so much crucial support wrapped up into one role, it is hard sometimes to deny SpD Tyranitar on more balanced "weatherless" teams. What is cool about SpD Tyranitar is that you have the massive special bulk on par with Snorlax, but without extremely crappy offensive presence. Ttar's movepool is so expansive you can mix and match to tailor your teams needs really easily, stuff like Twave and Roar that isn't slashed on the main set is still very viable.
Lead: The newest "main" TTar set. One of the most disrupting SR leads one can face and one of the most powerful outside of Terrakion and Garchomp. Not only can it mess up your weather first tier, but its varied coverage means you have no idea what is safe to stop it. Both physical and all special variants have been played to a degree of success. If you don't tred carefully, you can lose a Pokemon to an unexpected coverage move.
tl;dr