Ok so here is the Official Metagamiate viability rankings created by me,
motherlove, 
AllJokesAside, 
Ghoul King, 
Manchamp, 
Chopin Alkaninoff, 
OM room, and most of the OM community on PS!
Metagamiate Viability Rankings:
S-Rank:
Reserved for Pokemon who can sweep or wall significant portions of the metagame with little support, and Pokemon who can support other Pokemon with very little opportunity cost ("free turns"). Also the home of Pokemon who can easily perform multiple roles effectively, increasing their versatility and unpredictability. If the Pokemon in this rank have any flaws, those flaws are thoroughly mitigated by their substantial strengths.
 Lucario
 Medicham-Mega
 Noivern
A-Rank:
Reserved for Pokemon who can sweep or wall significant portions of the metagame and can perform well against most play styles, but require some support or have some flaws that prevents them from doing this consistently. Supporting Pokemon in this rank may give opponents free turns or cannot create free turns easily themselves, but can still do their job most of the time.
A+
 Arcanine
 Gliscor
 Metagross-Mega
 Slowbro
 Slowbro-Mega
 Weavile
 Zygarde
A
 Azumarill
 Chansey
 Charizard-Mega X
 Ferrothorn
 Garchomp
 Hoopa-U
 Jirachi
 Klefki
 Landorus-T
 Aerodactyl-Mega
 Talonflame
 Tyranitar
A-
 Heatran
 Mew
 Salamence
 Skarmory
 Starmie
 Tornadus-Therian
 Thundurus-Incarnate
 Venusaur-Mega
B-Rank:
Reserved for Pokemon who cannot sweep through or wall significant portions of the metagame, but can properly fulfill a given offensive/defensive niche. Support Pokemon in this category have flaws that prevent them from doing their job or are setup bait for dangerous sweepers. Pokemon who are partially outperformed by a Pokemon in A or S Rank, but are otherwise very dangerous, may also fall into this category.
B+
 Azelf
 Breloom
 Gyarados
 Hippowdon
 Keldeo
 Diancie-Mega
 Sableye-Mega
 Chesnaught
 Staraptor
 Togekiss
 Tyranitar-Mega
 Whimsicott
B
 Bisharp
 Clefable
 Crawdaunt
 Entei
 Diancie
 Exploud
 Gengar
 Latios
 Lopunny-Mega
 Sharpedo-Mega
 Terrakion
 Magnezone
 Forretress
 Quagsire
 Rotom-Wash
 Gardevoir
B-
 Avalugg
 Heracross
 Latias
 Pikachu
 Porygon-Z
 Swellow
 Tentacruel
 Zapdos
 Omastar
C-Rank:
Reserved for Pokemon who can be effective in the right setting, but either have crippling flaws that prevent them from consistently executing their strategy or are completely eclipsed by a Pokemon in the above ranks.
C+
 Blissey
 Hitmontop
 Luxray
 Hitmonlee
 Diggersby
 Golem
C
 Mr Mime
 Crobat
 Hariyama
 Machamp
 Suicune
 Jellicent
 Hawlucha
C-
 Abomasnow
 Bouffalant
 Linoone
 Banette-Mega
 Cradily
 Cloyster
D-Rank:
Reserved for Pokemon who have a small niche in the current metagame, but have very noticeable flaws that make them more trouble than they're worth the majority of the time. These Pokemon are, for the most part, unencouraged to use.
 Shedinja
 Gigalith
 Conkeldurr
Pikachuun can you add to OP?
(still waiting for Noivern suspect...)
Discuss any changes you wish to make and we as a community will determine its validity.