My rules are only 3 characters but I can do a few more characters with one big headcanon bc this is fun:

Chrollo always has his nose in a book during class. Probably not worth trying to talk to, because if he doesn’t completely ignore you, he’ll make little “mhmm’s” and “I see’s” in hopes he’ll appease you and get you to leave. His grades are okay, it depends really on what he wants to put effort into. Excellent papers on philosophical topics of course

Phinks and Feitan are the best. It’s entertaining but dangerous to have a class with them. Feitan’s the one who usually starts it, throwing papers at Phinks in class, pushing his seat away right as he’s about to sit down so he falls, calling him a dumbass whenever he doesn’t get an answer right. And Phinks is the dude who no one messes with because he blows up too easily so obviously he’s gonna turn around and start getting into a hugeeee argument with Feitan, yelling and cursing and shit and no one can stop them so it’ll last like the whole class. It’s just so funny Phinks will answer something wrong and Feitan will just whisper from behind him “Are you fucking stupid” and Phinks will snap at him “Shut up I’ll kick your ass”

Uvo cheats off on anyone and everyone because he sleeps 90% of the time

Shalnark is always on his phone of course. Gets it confiscated quite often, but he’ll just take out another little device right afterward. Knows how to access the school’s computer system, kids pay him to change their grades and absences. He doesn’t need to change his own grades because he gets those straight As, like he doesn’t pay attention at all in any classes, but definitely at the top of the class

Machi probably has classes with a few of the boys and she pretends she doesn’t know them (except Chrollo. Machi is the only one he’ll bother talking to) She’s very intimidating, everyone is afraid to talk to her