The problem with Dragon Tail Slowking is that it is ridiculously weak, and is set up on by half the tier, which is probably why no one uses it. What I've really been enjoying this round is Jynx. A simple set with Lovely Kiss / Substitute / Nasty Plot / Ice Beam can rip through the majority of the tier, given Jynx's fairly good Speed and excellent Special Attack. If given screens support, with opponent Scarfers removed, Jynx can easily blow past nearly any team. The only true counters are RestTalkers such as Munchlax.
I'm also enjoying Aerodactyl quite a bit. Everyone uses the Stealth Rock variant, but I have more recently opted for the Hone Claws variant, which can do some serious damage. Aerodactyl outspeeds the entire tier bar Accelgor, who doesn't OHKO with Hidden Power Rock / Ice, while Aerodactyl OHKOs in return with Stone Edge. The EdgeQuake combo when used in conjunction with Aqua Tail, gives Aerodactyl fantastic coverage, as a +1 LO Aqua Tail 2HKOs Claydol :o
Then again Claydol is literally the shittiest mon in RU right now........
One more lovely underrated mon is Sandslash. Sandslash is one of the few mons that can both set up Stealth Rock and use Rapid Spin. It has a great Defense stat as well as an above average Attack stat, so it isn't exactly useless outside of spinning. Claydol is wayy to weak and pathetic for my liking, and Sandslash seemed to fit the bill perfectly.