Do you have any general school-related head canons?
Apparently! Probably not what you're thinking though since most of the Koopalings didn't go to traditional school
Ludwig was definitely homeschooled as a kid and mostly was taught inside the castle once he and the rest were incorporated into Bowser's family, he did go to a little private schooling and has some one-on-one lessons with Kamek though, he's also definitely been and IS in rigorous army training.
Iggy+Lemmy's bio-parents didn't have the money to get both of them in school and since Lemmy was premature they ended up only sending Iggy to a public elementary, he didn't get any further traditional education beyond that. Nowadays Iggy tends to research on his own rather than enrolling in any course or schooling aside from troop training, he is secretly in a few clubs though, and he often visits the castle archives and pirates/steals documents.
Lemmy, having not gotten any schooling in his youth, was eager to enroll once he was adopted by Bowser, but found the stuffy private schools his new "King Dad" offered too difficult and stifling, so after he left middle school he begged to not go to any more. He did enroll in clown school one summer but that was mostly just for fun on his part, and he still has his graduation certificate from that.
Roy had the luxury of going to public school most of his life until getting Adopted into the royal family, however it can be said that he was NOT the best student, at all, he skipped most of the time and while he wasn't super disruptive, he also didn't do much work when he was there, late and missing assignments were a constant, and once he WAS living in the castle he wasn't eager to do anything aside from mandatory Army training, he did relent and at least let Kamek teach him how to use his wand though since he couldn't figure it out after It was given to him.
Wendy was also homeschooled when she was young but was always pretty social, if a bit bratty, once she was adopted by Bowser she eagerly accepted the offer for actual schooling, but she was also disappointed by the Private schools she was allowed to attend, fortunately she just happened to win her place in Bowser's favorites so she eventually convinced him to let her into a public school, where she actively flourishes even if she was a tad behind on some topics in the beginning, she also had a tutor when she was a bit younger.
Morton went to public school and has always struggled with it, refused to go to any similar schooling once he was adopted and so was mostly tutored inside the castle, he doesn't do well in group schooling so he often prefers one-on-ones when possible, and with the personal education Kamek could provide him he was able to get by, of course he avoided troop training for as long as he could but he does have to go to it eventually.
Larry does go to a private school but it's only twice a week and he mostly gets lessons within the castle the rest of the week, all of The Koopalings are in army and troop training and so is Larry so that's what he's doing most of the week, sometimes he gets training from the Majikoopa's though.
Junior does sit in on troop training sometimes but he isn't being taught yet, he mostly gets lessons from Bowser or the majikoopa's as well right now.
Not entirely sure this is what you meant, I had a lot more ideas than I thought I would though so I'm proud of this either way, hope y'all enjoy!! If you read all of em' then here's a fortune cookie 🥠