The Standalone Custom Co made by COW discord community, it would affect some gameplays or other weird effects.
Anyways here is the list of Custom Co made by community!
Eric Andre
Rick Harrison
Theresa Apocalypse
Knightlord07
Geese Howard
Chicken
Pearl
Miho
Darjeeling
Rina
Mengsk
Umi
Alps
Marie
Onceler
Mizer
Marisa
Slime
Lee
Emilie
Billy Gates
Jessabelle
Kage
Hanabi
Surge
Tondra
Kidd
Cyrus
Santa Sturm
Serena
Rance
Hammer
Conan
Yamato
Grendelle
Multiplier
Goenitz
Mr Krabs
Mario in a Kart
Dekks
Naked Squid
Nanoca
Padoru
Quackers
Goomba Tower
Enigma
Contessa
Great Minds
HMS Unicorn
Jod
Maho