A lot of things have been told in this thread, I did not adress them all (once I accidentially deleted my post in the editing window), so I will do that now.
First, Seismitoad, who is a huge boss. It can pull off so many things, and even when your opponent leads with it you don't know its exact set. Grass types are deadly afraid of Sludge Bomb, walls are afraid of Toxic, and only one weakness to an uncommon type in the meta thanks to Scolipede, though Seismitoad doesn't appreciate facing a Sun team no matter what as those teams run Solarbeam everywhere. Good, but not uncounterable though I admit I rarely faced well-played Toads. SubBU Braviary can freely set up on Seismitoad as long as it does not switch into Toxic which sucks.
Seismitoad partners well with Mandibuzz and Garbodor for a defensive core, much like others have said already in this thread, so I won't write again what's already written. However, this core likes Audino support or something because outside of Mandibuzz they don't have reliable recovery, and they are all somewhat vulnerable to status (especially Mandibuzz as the vulture prefers to stay in for a while which does not work when you have Toxic status).
Misdreavus is also ridiculously good in this meta. Though it cannot switch into some of the most powerful attackers in NU, the beheaded witch can defeat most threats in NU 1-on-1 when it has a free switch in and as such can check and counter numerous huge threats, from Braviary to Sawsbuck, from Sawk to Carracosta. Faster defensive variants also beat Skuntank and physical variants of Samurott (provided Misdreavus outspeeds and WoW hits in one try). It is an annoying and frustrating flaw that WoW misses just too often.
Then, there are two of the former drops I'd like to adress:
Jynx, after the initial hype, appears to have watered down a bit. I never had problems when facing it with my new team, (lol @ RestTalk Metang absolutely crapping all over it, provided no Freezehax (Rest doesn't work when frozen -.-)), but it still has Lovely Kiss as well as a powerful Scarf- or SubPlot set. However, Jynx absolutely craps over standard stall teams as well as frail teams, so it is a massive threat that has to be accounted for, and it can easily sweep teams if given a free turn or two.
The same can be told for Primeape, except that it can't sweep teams. The Ape is good, however, but I feel outclassed by Sawk and Gurdurr, despite its access to U-Turn. Sawk does have Taunt as well as that it hits way harder, while Gurdurr does hit less hard because of no access to Close Combat, it has semi-reliable recovery in the form of Drain Punch which works well with its absolutely ridiculous bulk. Gurdurr's bulk is absolutely sickening, taking pittance from anything and it has Guts to deter Status. Gurdurr is really good in this meta, give it a try. It can devastate entire teams, especially now Musharna is less common, probably because of Scolipede and Jynx which can prevent Mushy from doing much through Bug Gem/Life Orb Megahorn and Lovely Kiss/Trick, respectively.
About Rotom-F, well, I never used it much. I don't like that miss chance from Blizzard. ChestoRest looks decent on paper and it certainly looks better than Pain Split though.