I definitely asses stunting at tryouts. Our program has all HS age athletes try out together, not separately for JV or Varsity. We have our fall tryouts the last two weeks of August. Over the summer we will hold open gyms one to two times a week to begin to asses tumbling and stunting skills. These open gyms are not mandatory but 99% of our athletes attend each one. A majority of the athletes we have known for some time by the time tryouts come around and we can safely place them into groups. We have a three day tryout. On the first day, they learn a dance and cheer and then we do some tumbling. On the second day we review the dance and cheer and begin to stunt and more elite tumbling. We usually combine previous JV athletes with previous varsity athletes (especially if we are eyeing that JV athlete to make varsity that season) to see how they work together. It takes some tweaking but we usually end up with quite a few successful stunt groups this way. We first have them all go to extensions, if any of the groups struggle we will switch things up and try again until all groups are perfect. We then begin our one leg extended stunts and more advanced to spinning and switch ups when they are ready. This process has worked super well for us as a program! Let me know if you have any more questions!