Ranks A- and above, are ordered internally from most to least viable. Note that D Rank is reserved for Pokemon that are Ubers by tiering yet have no niche in the metagame — they are only in the Viability Rankings because we are obligated to put them there.
S Rank
S
Yveltal
Eternatus
Necrozma-Dusk-Mane
S-
Kyogre
Calyrex-Shadow
Groudon
A Rank
A+
Ho-Oh
Marshadow
Xerneas
Ferrothorn
A
Zygarde-Complete
Zekrom
Landorus-Therian
A-
Weavile
Darmanitan-Galar
Reminder that Pokemon below A Rank are no longer ordered by Viability within their subranks.
B Rank
B+
Aerodactyl
Lunala
Mewtwo
Rayquaza
Toxapex
Urshifu Single-Strike
B
Blissey
Dracovish
Landorus-Incarnate
Magnezone
Pheromosa
Shuckle
Zarude
B-
Buzzwole
Palkia
Slurpuff
C Rank
C+
Calyrex-Ice
Clefable
Cloyster
Giratina-Altered
Giratina-Origin
Zamazenta-Crowned
C
Dialga
Ditto
Excadrill
Heatran
Shedinja
Solgaleo
Tyranitar
C-
Audino
Dugtrio
Kyurem-Black
Magearna
Obstagoon
Reshiram
Rotom-Wash
Skarmory
Suicune
Tangrowth
Xatu
D Rank
A reminder that these Pokemon are only Ubers by tiering and possess no real metagame niche.
Cinderace
Genesect
Kyurem
Kyurem-White
Lugia
Naganadel
Necrozma-Dawn-Wings
Spectrier
Zamazenta-Hero