BO Tier List:

S Rank:
Altaria-Mega
Hydreigon
Krookodile
Latias
Scizor
Terrakion

A+ Rank:
Aerodactyl-Mega
Primarina

A Rank:
Celebi
Doublade
Infernape
Mamoswine
Manectric-Mega
Rotom-Heat
Slowbro
Togekiss

A- Rank:
Amoonguss
Bisharp
Klefki
Nihilego
Steelix-Mega

B+ Rank:
Aggron-Mega
Cobalion
Diancie
Empoleon
Gligar
Hippowdon
Kyurem
Lucario
Moltres
Slowbro-Mega
Suicune
Tsareena
Volcanion

B Rank:
Alomomola
Bewear
Blastoise-Mega
Crawdaunt
Florges
Roserade
Rhyperior
Starmie
Swampert
Sylveon
Tentacruel

B- Rank:
Azelf
Bronzong
Feraligatr
Heracross
Jellicent
Mienshao
Muk-Alola
Nidoking
Nidoqueen
Zeraora

C+ Rank:
Barbaracle
Chandelure
Haxorus
Magneton
Mantine
Reuniclus
Rotom-C
Salazzle
Sceptile-Mega
Seismitoad
Snorlax
Stakataka
Toxicroak

C Rank:
Araquanid
Chesnaught
Cofagrigus
Crobat
Linoone
Necrozma
Palossand
Pidgeot-Mega
Shaymin
Talonflame
Tornadus
Umbreon
Zygarde-10%

C- Rank:
Absol-Mega
Articuno
Aurorus
Beedrill-Mega
Decidueye
Hoopa
Mandibuzz
Pyukumuku
Quagsire
Sandslash-Alola
Silvally-Steel
Xatu

Sewage Rank:
Blissey
Cresselia
Durant
Ferroseed
Marowak-Alola
Metagross
Porygon2
Registeel
Venomoth