Depends!! I consider "All-Star" and competitive cheerleading a sport. Sideline cheering?? I do this, and no, I don't think sideline cheering is considered a sport. It totally is physically demanding and stressing, for sure!! But it's more of an activity I feel like (although under schools it could either be considered a club, extracurricular, or a sport- it is listed under the athletics programs at my school). Competitive cheer doesn't have pom poms, so if they have pom poms, it is not a sport!! XD
Just my thoughts :p