Things are ever-changing in the South where football and cheerleading are taken so very seriously. My daughter was a cheerleader for the city in a leage, then one for cheerleading, but she was suspended due to cheating on a test. She had ADD and they refused to give her accommodations as she was supposed to get and she rebelled. The sponsor kicked her off for the year and our fight for a suspension only won the appeal but the sponsor did ugly stuff to turn the girls against her. No other group (football players or honor students) were dealt with so harshly. So that's a good thing to know. The schools will hold her to the highest standards and kick them off for proof of high school drinking, etc., etc. Make sure she is informed if she grows up to be a HS cheerleader.
She didn't have gymnastics but the best ones did. I recommend that because they like to win competitions.
They have special cheerleading lessons at gymnasiums, some only specialize in that. Check them out. Ask the junior high sponsor where she'll go to to recommend the best one and why.
She had to have a custom cheer to try out. I can't remember how we found a college gal to make one up for her (to play to her strengths), but I credit her for getting her foot in the door. The routine focosed on snazzy with sharp moves and a little hip action. I coached her on giving eye contact to the judges and flash a cute smile and give it personality. Being very animated and flipping that pony tail.
Lastly, they need to have social strengths and high self esteem. If they are shy, or don't care about grooming, or how to be outgoing and personable to many, that will get in her way.
It teaches them some great girl skills. Don't forget to try to get in some team skills from games like T-ball (so they can learn to handle criticism, teamwork, a few hits, and the spirit of competetiveness).
Good luck. A busy, involved kid doing what they like and getting quality time with parents and good self esteem and learn to take advice to achieve their goals will go a long way toward their being able to fend off drugs and (hopefully) "bad boys" down the road.