Poor Hera. :( But eh, it's easily prepared for now, and Mienshao is the Top Fighting-type of UU. Sorry Hera, but Mienshao is da baws here. (hell, Mienshao should be the #1 most used Poke in UU right now)
Anyways, supporting Cofagrigus for S-Rank simply because it's the quintessential Ghost-type of UU. It can fulfill numerous roles in one set. Cofagrigus is the ultimate spinblocker; basically if you're running a Spiker, like Roserade, Froslass, or Qwilfish, Cofagrigus is an amazing teammate to ensure that Blastoise or Claydol of theirs doesn't get rid of your hazards. Not only that, but it's a hard counter to some Fighting-types such as Mienshao (which being able to make this thing useless is amazing), as well as Heracross along with some others. Mummy is a wonderful ability, neutering some great abilities such as Mienshao's Regenerator, Krookodile/Heracross's Moxie, Azumarill's Huge Power, and more, which is another plus. This also makes Cofagrigus a strong wall, the defensive set is great for stall, so if you need a spinblocker/wall for a stall team, this is it. OTR set, the common claim to fame of Mr. Cofag, is also a strong sweeper, and with the Spikes support that Cofag will make sure never gets off the field, TR+NP is vicious and will wreck anything that doesn't have great special bulk. Two-turn setup is kinda ball, but Cofag can definitely handle it. Trick Room is also a great assistance to some vicious Pokemon such as Druddigon, Escavalier, and Rhyperior, all of whom can wreck shit in there. Overall, Cofagrigus is very reliable and versatile, and I've probably used this thing over any Ghost-type in UU 'case it's so reliable. Definitely an S-Rank Pokemon.
I strongly disagree with Raikou being moved to A-Rank. If you don't know already, here's the thing: Raikou is the pinnacle of special sweeping. SubCM is so deadly, that if you don't prepare for it: You're going down. Raikou has the bulk, power, and speed to just outright sweep everything after some boosts. Thunderbolt+HP coverage is nothing to be trifled with. It's one of the best late game cleaners around. Keep it in S-Rank.
On another note, we should add Sigilyph to the list somewhere. Its Cosmic Power set is capable of being a bitch to face, and its Magic Guard is nice to prevent passive damage. It can take on Fighters and cripple shit with burns, and after some boosts, it can be really powerful. It is prone to crits along with Haze/Whirlwind isn't an immediate threat either. It can also go for offensive CM and hit rather hard with usable coverage. That said, it does have an awkward Speed tier and packs some exploitable weaknesses, but for now I think C-Rank should be a good start for our fellow ancient bird thingie.