Why does the OP need to see his doctor? What will a doctor possibly say other than the numerous weight-loss tips offered (for free!)? There is some silly BS that has been put forward, but for the most part, if the OP follows the advice of some of the posts on here, he will lose weight. I guarantee it.
The doctor is not a nutritionist, and out of fear of being sued in the event he (she) is wrong, will fail to give any real, solid advice. Sure, they will test for blood pressure & any abnormalities, but for crying out loud - he's an overweight male teen. He isn't a geriatric, morbidly obese person who can barely walk.
Hit the exercise hard, recover well (adequate sleep), eat clean with sufficient macronutrient ratios for your goals, and limit excess consumption. Following exactly this program will result in fat loss. I am so confident I'd bet a year's salary on it.
I'll grant that if he has no health insurance and would have to pay $200 or something out of pocket, it's probably not worth it. But assuming he (or his family) does, a $10 copay to set realistic goals and pace with a health professional who has his history is not a stupid idea. Not to mention a referral to a nutritionist which would absolutely be a good idea to steer him away from all the contradictory crazy diet advice he's getting for free.
As you say, if he follows "some of" the advice he's getting here for free he'll do fine. But I have teenagers and I wouldn't assume that a teenager can easily sort out which is the good advice and which is the bad.