I've used Rocky Head Tyrantrum quite a bit and it feels more like a B- rank to me, but C+ seems like a pretty good place to start. The Choice Band set is a pretty good wallbreaker/nuke who is able to take advantage of Talonflame, a big threat to a lot of teams, and is very difficult to switch into. Just to give you an example :
252 Atk Choice Band Tyrantrum Head Smash vs. 252 HP / 252+ Def Mega Slowbro: 163-193 (41.3 - 48.9%) -- 80.1% chance to 2HKO after Stealth Rock
This is the most physically bulky Pokemon in that game in terms of raw stats, besides Aggron and Steelix who are never seen in OU. And keep in mind that Mega Slowbro doesn't usually run that much defense. Needless to say, everything which doesn't resist Rock is 2HKOed by Head Smash. If you account for its coverage (Head Smash, Outrage, Earthquake, Fire Fang / Superpower will probably end up being standard), its counters are limited to Hippowdon, Chensaught, and Mega Aggron and Steelix (lol) The things which switch into Head Smash tend to be auite easy to take advantage of too, this means that Tyrantrum
Obviously it has some pretty glaring flaws, it has a hard time switching in on anything due to its large number of weaknesses and pretty much requires pivot support in order to do its job, not to mention that Head Smash's accuracy is pretty infuriating at times. Its bulk, while good, isn't really enough to compensate for its typing. Ferrothorn is pretty common and while it gets steamrolled by Superpower and Fire Fang, it prevents Tyrantrum from mindlessly spamming Head Smash which is all it ever wants to do. Most notably, it has some pretty big competition with Tyranitar as a banded wallbreaker, since it has higher bulk on both sides of the spectrum and access to Pursuit which enables it to double up as a trapper. However, Tyrantrum has a few advantages over TTar. Obviously, it hits way, way harder as mentioned above. It also has access to Outrage, which is pretty big since that means it's not a free switchin to every single fighting type, notably Keldeo who shrugs off anything TTar throws at it, but is OHKOed by Outrage after Rocks. Outrage also has a chance to 2HKO Hippowdon depending on defense investement, does a number on Chesnaught. Finally, there's the extra speed, which seems minor but is actually a huge deal since it enables Tyrantrum to outspeed base 70s, specifically Bisharp who can just smack TTar with Iron Head, as well as Pokemon taht specifically speed creep Jolly Bisahrp like Celebi and Landorus-T. You also outspeed stuff like Adamant Gyarados, Modest Gardevoir-pre mega, that kind of stuff. While Tyrantrum's Choice Band set is basically useless vs offense outside of checking Talonflame, it excels vs slower teams which will have to take a hit from it at one point.
The Choice Scarf set is also viable. Once again, it suffers a lot competition from TTar, but it's actually able to, thanks to its greater speed, outpace Tornadus-T which is a pretty big threat Scarf TTar fails to check. Also, higher power on your main STAB can never hurt. I would not bother with DD at all, not only does Tyrantrum have a very hard time setting up, Head Smash's bad accuracy makes it a unreliable move for sweeping. Just stick with the choiced sets for this thing. As far as I can tell it isn’t the kind of Pokemon you really build around. If you need it for any reason, it’s there, and it does its job pretty well.
Concerning other Pokemon :
Hippowdon is just really good rn, I don't think it's much of a stretch to consider it as on par with Celebi or even Slowbro. What it loses out on in terms of momentum, it makes up for in just the sheer amount of stuff it handles. IMO the best set right now it the physically defensive one, it's a fantastic answer to Lopunny, Landorus-T and Talonflame, it can also handle huge threats such as Bisharp, Pinsir and XZard, and it's just obscenely physically bulky in general. But the SpD set is also very solid, it handles Thundurus, Gengar, Diancie, YZard (kinda). Its great bulk make it a fantastic rock setter because it pretty much doesn't die from any single hit and forces out a lot of stuff. Hippowdon is just really easy to fit on teams just because of the large amount of things it handles. There are so many teams where I think "I need something to beat this this and this and set up rocks" and very often, Hippowdon fits the bill perfectly, so from a teambuilding perspective it's definitely worthy of A, though due its status as a momentum-killer this may not translate too well in-battle.
On the other hand, I don't think Starmie should move up to A. Obviously, if there's one set which is A worthy it's the bulky spinner set, and though that set is definitely good, it does suffer from a few problems. The first one is 4MSS. Before, Starmie could easily get away with Rapid Spin / Recover / Scald / Reflect Type. But now, a lot of Starmie have started to run Psyshock for sub CM Keldeo which has become really popular. This means Starmie loses Reflect Type, which prevents it from handling Ferrothorn an turns it into Bisharp fodder. Then there's the fact that it's setup fodder for the likes of MGyarados, XZard, MAltaria, Serperior, Sableye (which spinblocks it), Celebi, MSlowbro, Manaphy, and CM Latios whcih means it actually needs a good amount of team support if it doesn't want to get blown in half. Add to that the fact that it suffers competition from Tentacruel (who can actually beat Sableye) and that Pursuit TTar, a very popular Pokemon on balance, flat-out removes it, and I can't see it moving up.
Sableye drop, like the Hippowdon rise, is something I've been thinking of for a while now. I think the Sableye hype is pretty much over it this point, and now that people have adapted to it, Sableye isn't as amazing as we thought it was. Pretty much every team has something that can break it at this point, and it's not like these Pokemon are necessarily bad or easy to take advantage of. Gliscor is an excellent Pokemon which beats Sableye. Same for Manaphy, Clefable, Sub CM Keldeo, SD/BU Talonflame, Landorus for the most part... And that's not even going into all the megas that beat it without even thinking. Now obviously, just because a lot of stuff beats Sableye doesn't mean its bad at its job : it's still an outstanding hazard preventer. However, it forces a certain type of build on the user. Sableye is absolutely not a Pokemon you can just slap on a team that's weak to rocks and call it a day. It's very difficult to use successfully without specifically building round it, because by using it, you leave yourself open to so much dangerous stuff that you have to compensate for it in 2-3 teamslots. And honestly, I don't really think a Pokemon which constrains your teambuilding this much can be S rank.
Support a Magnezone drop, it's a nice trapper and offensive fairy check but it's just so often a liability it's not even funny. Half the time you can't even trap what you want to because then XZard just sets up in your face. And then there's the fact hat a lot of Ferrothorns run Shed Shell now, so you kinda need to pair it up with Knock Off Azumarill or Lando-T for it to be reliable, But mostly the reason I feel it should drop is because it's so easy to just turn the tables on it.
Finally, any reason Serperior didn't rise? There was a bunch of discussion on it and I don't remember anyone being opposed to it.
i guess that means he co-runs the thread 
