I measure whats a sport or not with two factors, degree of physicality and degree of competition. Now cheer-leading isn't necessarily competitive except for those actual cheer competitions. Here's the thing though, I wouldn't consider something where the opposing teams or persons take turns doing something a sport, unless of course the degree of physicality was that much higher, for instance, I wouldn't call bowling or cheering sports, but I would say that pole-vaulting would be a sport. In short, no, I don't think cheering is a sport, besides, if you look in the stands you'll see the fans have way more pageantry than the cheerers.