Okay, after a lot of testing, I've decided to Suspect Clefable.
It was inevitable, an OU Pokemon in such a metagame would be strong. So strong that it was nearly unbeatable for most teams even, lacking counters and had a way to defeat every single counter. Arbok, Nidoqueen, Garbodor? Psyshock. Ferroseed, Klefki, Mawile? Fire Blast. After this only defensive Fire types could reliably beat it, but we only have Ponyta, Braixen and Growlithe, the first two being setup upon by the Calm Mind + Softboiled Set and while the other one could Roar, it had nearly no other purpose in the Metagame, existing solely as a Clefable Counter. Despite it's speed, only a select amount of Pokemon can revenge kill it, because it has huge bulk. This means that it will usually take 2 or more Pokemon down, if you have Sticky Web support, it can easily sweep entire teams even. Due to Magic Guard, it can even run Life Orb without any negative impact!
Viable Offensive Clefable Sets:
Calm Mind + 3 Attacks
Calm Mind + Softboiled + 2 Attacks
Cosmic Power
(Maybe Specs, I'm not sure, didn't see it)
Defensive:
Unaware Wall
Supportive:
Healing Wish
Dual Screens
Wish Supporter
There might be even more sets, but this should prove that it's very versatile. Besides that, it's sets can also fit on any type of team, aiding to it's viability.
TL;DR: Clefable is a crazy strong Offensive Wallbreaker/Sweeper (Despite it's speed), it can also run a defensive sets for Stallier teams and have all kinds of supporting roles, just as the other sets, fitting in a lot of teams. (Fairy type is awesome too)
So any thought on Clefable? to vote, put Ban or Don't Ban in your post
Personally: Ban
if anyone wants a battle to test this, or other threats. I'll be on main in the Other Metas room (or just do /whois) and on my server