It depends..... in some areas of the country stunting is not allowed. In other areas such as Georgia, high school teams are doing stunts just as difficult as level 5 all star teams. Therefore, I wouldn't say that high school stunting is simple or should be allowed everywhere. It just varies by skill and ability level. A prep for one team can be just as dangerous as preforming a full up for another team if proper form and technique are disregarded. Also, she may be unfamiliar with stunting and be uncomfortable trying to teach it. Therefore it would be a safety liability not only for you all because you haven't been coached by a knowledgeable staffer, but also for her if one of you gets injured because she let you all do something that wasn't legal/safe unknowingly. While it may be frustrating, i would look at the situation in her shoes......many times teachers are just thrown into the "cheer coach" position with minimal experience and may be overwhelmed.
You may want to stick with allstars in this case if you really want to stunt, as it might not be a good idea to fight the coach/school board about this (and honestly if the girls have little stunting experience it would be basic progression stunts used at games anyways).