Remember to check the FAQ and "How do we weight classes?" sections if you have any doubt regarding the ratings.
Fire
Water
Thunder
Forest

SS

Completely broken units; most are reliant on dupes. These units should never leave your main roster once you've built them.

Mia: LS
BT3
Mia: LS
Dantang
BT3
Dantang
Hati
BT3
Hati
Jona
BT3
T
Jona
Giles
N
Giles
Azure
Azure
Fia
MBT
Fia
Sheol
T
Sheol
Vice: KS
N
Vice: KS
Reinhardt
BT3
Reinhardt
Michael
MBT
Michael
Hiiro
BT3
Hiiro
Minos
T
Minos
Jeriah
T
Jeriah

S

Meta choices. Capable of handling 99% of the game; in fact, the high end S tier units here are capable of hitting the peaks that SS units have. However, they often require a little more support.

Charon
BT3
+
Charon
Mia: LS
+
Mia: LS
Hati
+
Hati
Victoria
+
Victoria
Sinsa
+
Sinsa
Leona
+
T
Leona
Patty & Patsy
+
T
Patty & Patsy
Dantang
Dantang
Gram
Gram
Nails
N
Nails
JOKER
-
JOKER
Frostfire
-
Frostfire
Tohru
-
Tohru
Regina
-
Regina
Benny & Curo
MBT
-
Benny & Curo
Schwartz: AC
BT3
+
Schwartz: AC
Fia
+
Fia
Bethel
+
T
Bethel
Nina
BT3
+
Nina
Mu Yuebai
BT3
+
Mu Yuebai
Regal
Regal
Sharona
Sharona
Fleur
Fleur
Connolly
Connolly
Vic
N
Vic
FOX
FOX
Corax
MBT
Corax
Vice
-
Vice
Wrath: PF
+
Wrath: PF
Leyn
BT3
+
Leyn
Michael
+
Michael
Tessa
+
T
Tessa
Requiem
Requiem
Reinhardt
Reinhardt
Luke
Luke
Revy
Revy
Xuan Ji
BT3
Xuan Ji
Wrath
Wrath
Eve
BT3
Eve
Schwartz
MBT
Schwartz
Amemori
-
Amemori
Leo
+
Leo
Beryl
+
T
Beryl
Areia
+
T
Areia
Odi
+
N
Odi
Lenore
Lenore
Hiiro
Hiiro
Paloma
Paloma
Migard
Migard
Mythos
Mythos
Joshua
Joshua
Barton: DB
N
Barton: DB
Cuscuta
-
Cuscuta
Robyn
-
Robyn

A

Off-meta units that can still be pretty potent in their own right. Many units in this tier still hold respectable niches or impressive damage; however, they firmly require team-building or luck to hit their maximum potential.

Jona
+
Jona
Benny & Curo
+
Benny & Curo
Taki
MBT
+
Taki
VIOLET
VIOLET
Rouge
Rouge
Barbara
Barbara
Nails
Nails
Momo & Anzu
-
Momo & Anzu
Kristen
+
Kristen
Corax
Corax
Beretta
Beretta
Allura
-
Allura
QUEEN
+
QUEEN
Sadie
+
Sadie
Vivian
MBT
+
N
Vivian
Dayna
+
Dayna
Xuan Ji
Xuan Ji
Eve
Eve
Schwartz
Schwartz
Erica
N
Erica
Hachi & Gin
Hachi & Gin
Kafka
Kafka
Mia
N
Mia
Kanna
-
Kanna
Sanae
-
Sanae
Lola
Lola
Yao
-
Yao
MONA
-
MONA

B

Units that can either be useful for newer players or players struggling to complete their teams. Still capable of holding their own when given support, but doesn't scale very well in harder fights.

Cordy
Cordy
Rainbow
+
Rainbow
Kuma & Pengy
+
Kuma & Pengy
Elma
Elma
Constantine
Constantine
Isa
Isa
Vivian
-
Vivian
Casta
Casta
Dawn
Dawn
Li Tianxian
Li Tianxian
Joselyne
Joselyne

C

Playable, but only barely. Units in this tier are not really capable of clearing the hardest content in the game, even with proper support. Play them only if you want to tinker around with janky effects, or have particular attachment to a certain unit while you do your dailies.

Chandra
+
Chandra
Luo Song
Luo Song
Jane
Jane
Bonacie
Bonacie
Lester
+
Lester
Clover
Clover

D

Bad beyond the early game.

Chainsaw Rick
+
Chainsaw Rick
Sork & Bekk
Sork & Bekk
Korgon
Korgon
White Dwarf
White Dwarf
Angel
Angel
Jomu
Jomu
Leah
Leah