Douma and Teruteru
I feel like Akaza, Mahiru, and Tenko would absolutely team
Nakime and Chiaki would get along decently
Gyokko MIGHT be able to befriend Korekiyo
Hantengu... I honestly feel like pairing him up with Chihiro because both of their emotions are very obvious in visibility, and they both have a timidness issue
Muzan... not sure about him.
WAIT
NAGITO
"Let's kill a bunch of humans! It'll bring so much hope to this world!"
"Uh- yeah- yeah, whatever you say, kid..."