I wrestled for 5 years in shcool. It was a good thing. You get in and stay in great shape over the winter, at 15 the working out is fun, not like lifting weights, more running, and jumping, team drills that are fun. It will help you develope your body at a time when its important. It also increases flexibility and joints wich is great becuase it means you dont get hurt as bad if you take spills dirt riding. When you join the HS team everyone knows your a wrestler and that tends to keep the lame bully types in check in and of itself wich is really like 90% of the battle, just avoiding confrontation by deterance. As far as real fight skills, yeah it helps, as a wrestler the most anyone could get in at me was one swing before I had them on the ground, most fights, a guy would take a swing and miss and be on the ground before his swing was done. Once on the ground very painfull submissive holds had my opponents agreeing to behave once released. If a crowd was present, the banana split was always a humiliating compramising hold as it more or less threatens to tear ones crotch appart :) .
Word of caution, wrestleing was very hard on my knees over the years, I advise wearing soft knee pads from the start to avoid initial injury caused by repettitive abuse from practiceing shoting. Some guys would wear just one knee pad on their shoting leg, but that is a tactical mistake as it lets your opponent know wich side your shooting from, I wore two. Also, its YOUR call to try to gain or loose weight, if you become a decent wrestler, let your body dictate its own weight, I gained weight every year from adding muscel and just normal groth at that age, dont let anyone tell you to gain or loose weigh, if your good youll get a varsity spot at any weight class your in and other JVs can either get better skills or adjust their weight class around you.
Sign up and enjoy! its fun, gets you in shape, and you can whoop football players butts if it comes down to it, your a trained fighter.