flexible gymnastics

Well to be honest, flexibility varies a lot even among gymnasts. Probably the two most important things are to be flat to the floor in front splits, and to be able to do a bridge. That said, I was always terrible at bridge, and another girl in my group was nearly a foot off the ground in side splits. That girl went on to become a very successful Lv10er.
It really depends on what skills you want/have to do.