I struggled with this. It was hard for me to gain any real mass as a teen.
I’d generally recommend teens avoid supplementing with protein shakes. I appreciate the challenge of a highly active teen that isn’t ready/capable on focussing on nutrition. Sometimes supplementing protein is perfectly safe and acceptable for “super fussy” eaters. Like anything else, there are trade offs.
Before supplementing, I’d definitely book a consultation with a nutritionist. Get him to define clearly his goals, and build out a plan. Supplements might be part of it but there it is no silver bullet.
I know that didn’t really answer your question, but I hope it helps anyway! I’d love to hear how things progress regardless of the path you take! 💪🏼