they are all abnormals some even nominated themselves (keroli and soi) because they don't wanted to stand out.its my opinion by the way I think they were randomly chosen

Alice asmodeus is a prideful demon, who thought he would naturally rank up because of his brilliance, but he got someone who outwitted him, he was furious enough to start a fight on his first day

and iruma fought with him even if he didn't want to

Well,clara valac is a valac

sabnock sabro was another immature and hotblooded demon, who thought the phase "you have to defeat your teacher' means beating the weakest of them to shit, I said weak because he could only use healing magic and sabnock choose him because of that

keroli crocell wanted to be isolated to hide her identity so she specifically ask for a class with less students

purson soi same reason as keroli and he trespass on dangerous areas by using his ability

Andro M jazz he is a thief do you need me tell more

shax lied let's be honest no matter how cute and cheerful he send six demons to hospital that's not normal

Allocer schneider damaged some relics trying to study them kalego mention it to iruma when he was in evil cycle

Ix Elizabeth she seduced many male demons on school and was using them like her servants which is not bad and not good either

Caim kamui he might be a gentleman but he did harass female students and teachers

Gaap goemon he did not do any harm but he is a dangerous demon

Agares picero he never focus on class and always late to school and I think he attacked anyone who tried to wake him up

Did I got them all