Copywrite Question regarding Nintendo Characters?

So my friend and I wrote a show to be put on as a one act for our school (All money being donated to charity). The story is unique, but the characters are from Super Mario Bros. We literally take Mario, Luigi, Bowser etc. and kind of did a "Wicked", where we told a different story with the same characters. Anyway, the show turned out to be a hit. Far more successful than anticipated. So we were told that we should take it to the Illinois theaterfest, a gathering of high school drama clubs, and perform there. However, I dont know what copywrite laws might be standing in the way or how to fix them. So... Are there rules against this if no one makes money? What are they? How do I abide by them?