Going back to the Mutant academy thing....
How many schools for teen Mutants have there been in the comics?
Jean Grey School(the original)
Whatever school Cyclops had that replaced it.
But there's also been the original Hellions group sponsored by the Hellfire Club and lead by Emma Frost.
The Acolytes didn't really have a proper academy, BUT... they had a space station team base, and teen recruits to their super team.
The Avengers had the Avengers Academy, which, while not tailored to Mutants, did apparently have at least a few.
Then you have the weird stuff...
X-Statix, while not a proper superhero team was a sort of training ground catering to Mutants all the same.
Then we have Clan Akkaba. At first you're like "What? The guys who are Apocalypse's personal cult?" Well... they're also his descendants, and presumably each generation of clan Akkaba trains the next in how to be clan Akkaba. While we don't know HOW that happens(since Akkaba stories focus on adult members), we do know that it happens.
Hmmm a story using those groups as influences on impressionable young Mutants? heheheeh