Ok after playing some B/W on Po i feel i can give a little insight. =P
Stall is still usable (woot). Hard and annoying to break as ever. Bulky offense seems to be the most popular though.
Nattorei and Shed Shell Forretress seem to be the only Spikers people use. Havent seen Skarm at all which is strange since it beats Ononokutsu into the ground with even just Drill Peck. Taunt sucks on it because it has the bulk of a wet shoe.
Ghost/Water is common and rather annoying and is like on 1/3 of teams.
Rest Talk Dragon Tail Gyarados and Milotic (especially the former) make cool dragon checks. Really though Calm Rest talk Milotic is amazing utility, being able to own stuff with Boiling water and PHaze is a great addition to it and it just doesn't die with Marvel scale. It also checks Zoroark and NP Luke.
Ground/flying legendary genie is on most teams serving as a check to the dumb mole with EarthEdge U-Turn and Explosion aswell as SD.
Jaroda is immensely annoying. +2 sp.att boost every leaf Storm frikking hurts.
Garchomp has been...underwhelming so far, same with Ononokutsu, Shandera, Salamence and Lati@s. Darkrai is annoying though lol.
Zoroark is ridiculous. Really, make one stupid switch and it shreds your team to bits. Though i mean making stupid switch ins is common due to its disguise. What a peen lol
Mole is annoying and my god is it powerful. Ive also been struggling with Terakion and Rankurusu (Magic Guard and Recover = ughhh). Both are ridiculous to be quite honest. Same with Kerudio.
Scarf Ditto is amazing. Has been my stall teams MVP.
Scarfchomp, scarf Onono seem to be popular too.
Genosekuto is just....ugh. Take this literally, if you dont have Blissey or Heatran you WILL lose. Its like porygon-z on crack, - nasty plot + better typing, movepool and rock polish. My Snorlax took 45% from LO Download Bug Buzz. @__@
Kojondo is a popular lead along with the Spikers and some Magic Coaters too.
Mischievous heart Sableye gets away with annoyingly Taunting, Recovering and Burning everything. Similarly, Victini makes me rage. >o
Technician Breloom with Mach Punch and Bullet Seed omg does this thing hurt. >_o
I really dont know what the heck im doing rofl. Some of the time im just switching blind into things, i really need to learn more. XD