"What In Hell Is Bad?" Character Tier List

 Since I can't find any actual tier list based on their battle utility online...

Official Website / Character's sexual paraphilias / Character Info Masterlist

Characters:

The Seven Kings of Hell

Beelzebub (Gluttony)

Mammon (Greed)

Satan (Wrath)

Leviathan (Envy)

Asmodeus (Lust)

Belphegor (Sloth)

Lucifer (Pride)

The Demons of Ars Goetia

Gehenna (ruled by Satan)

Leraye

Sitri

Paimon

Astaroth

Zagan

Belial

Tartaros (ruled by Mammon)

Bimet

Eligos

Hades (ruled by Leviathan)

Barbatos

Foras

Glasyalabolas

Abaddon (ruled by Asmodeus)

Phenix

Dantalian

Ronove

Paradise Lost (ruled by Lucifer)

Marbas

Morax

Buar

Avisos (ruled by Beelzebub)

Stolas

Bael

Amon

Naberius

Niflheim (ruled by Belphegor)

Gusion

Bathin

Andrealphus

Angels

Gabriel

Michael

Raphael

Humans

Minhyeok

Solomon

TIER LIST*:

S (useful for dailies, farming)

Satan (Selfie) (current widest DMG range in game)

Beelzebub (Selfie) (used to clear crowdiest wave of mob)

Leviathan (Selfie) (debuffer upon Ultimate)

Leviathan (Bath) (placed at corner, at least 3x3 away from others)

Marbas (pure healer)

Bimet (individual shielder)

A (useful, can be used as placement for S-tiered characters)

Mammon (Selfie) (stunner, placed at upfront)

Belial (better stunner than Mammon)

Dantalian (passive ATK speed buffer)

Minhyeok (replacement for Satan)

Paimon (ATK speed debuffer)

Eligos (shielder+tanker)

Morax (placement for Marbas)

Buer (individual healer)

Glasyalabolas (ATK speed debuffer)

Phenix (skill gauge buffer)

B (somewhat useful, though not necessary)

Leraye 

Bael

Stolas

Ppyong (stunner)

Astaroth (poisoner)

Stolas

Gusion (stunner)

Ronové 

Barbatos (trapper)

Gaejuki

C (not totally useless)

Amon

Naberius

Ppam (DMG reflector)

Ppang 

Harumon

Ppolppol

Ppyongppyong

Red Ragnarok (individual healer)

Rob Van Dam

John Cena

F (useless)

Zagan

Valefor (seriously, 1s?)

Ppungppung 

Undertaker

Bella

Max

Leo

Toto

Molly

Booker T

Bob Marley

Lucy

Bailey

Urupapa

Darkness Weapon

Fishball

Nightslave

Oni

*Based on personal experience, may lack some characters I currently don't have.

Check character skills here.