I personally don't see what all the Clefable fuss is about. Much like big sister Blissey, it is a powerful doorstop to the majority of offensive threats, and it can take the offense with specialized movesets for specific switch-ins (Facade for Hitmonlee being a perfect example), or the requisite CM/BoltBeam set, but beyond that, it is set up bait. Yes, it gets Encore, but I'm the only person I've ever seen run it. Without it, NP Toxicroak, SD Leafeon, Dragon Dance Altaria (the latter two assuming no Ice Beam, obviously), some of the biggest setup threats in UU, can walk all over it, and Focus Punch Aggron can do so regardless with a good outprediction. And even if it does run Encore, that's one less viable moveslot, meaning it can't nearly as easily get away with run Wish/Protect (or Protect in general, even if it is tempting to run with Encore), SubPunch, or CMBoltBeam.
It also serves as one of the few "true" counters (sort of) to the one poke that I feel absolutely needs to be discussed that isn't getting treated- Jumpluff. Seriously. I've been going apeshit on the UU ladder with this guy today. Jumpluff alone has gotten four people to quit in UU (and one in OU when I hit the wrong ladder button). SubSeed alone can stall out entire teams at times given that he's tied for third highest natural speed in UU, easily outdamaging Stealth Rock over the course of a match (and being deadly in tandem with it).
At this point you probably want to bring up Grass types as 100% counters to Jumpluff's SubSeed shenanigans, consider Jum rarely if ever runs an attack off those base 55 offensive stats. But when you consider that, in UU, Grass types run the Aromatherapy game, you have to compound the value of Jumpluff's Sleep Powder against them. Vileplume and Meganium aren't doing a damn thing about your Toxic'd Lanturn or your paralyzed Swellow if they themselves are completely incapacitated by the third most accurate sleep move in the game. And once that vital grass type is asleep, you're obviously in a tight spot. Do you switch out, and let Jumpluff keep SubSeeding through until it finds the move that, when Encored, opens the window to sweep your team, or do you leave the grasser in and wait out the sleep?
And oh, Encore...what a fine move Encore is. I wanted to give it it's own paragraph, and I guess I did, but honestly, when you've got something with an EQ immunity, a 4x resistance to something that several prominent walls bear a 4x weakness to, an immunity to Leech Seed and Toxic Spikes, Substitute, and a base 85 SpDef with Surf resistance, I'm sure you can think of your own Encore hijinx.
The only time Jumpluff hasn't at least either stalled out 200% total health from the opponent's team, slept a threat, or opened the window for one of my own was when I switched it into Lanturn's Thunder Wave, expecting Surf. It was the single most heartbreaking moment I've had on the UU ladder. And it was poor playing on my part, and obviously has no bearing on Jumpluff's abilities.
Edit: Oh, and while I'm at it, if I'm going to advocate Jumpluff moving up, I'm advocating Steelix go with it. Seriously, the only physical attack I've seen 2HKO this thing was Banded Hitmonlee's Close Combat (I'm not sure if Life Orb does as well), which I believe is going to have the highest damage output of any physical attack on Steelix in UU, barring something that requires a set-up or switch-in like Hitmonchan's Focus Punch. Considering his Toxic immunity and ability to 2HKO most other UU walls that can hit him super-effectively, like Quagsire or Nidoqueen, the only sure-fire ways I've found of shutting him down are surprising him with Vacuum Wave Toxicroak (it OHKO's with a single Nasty Plot) or stalling him to death with my favorite current UU, Jumpluff.