Ok, so how does he get swole in 2 months before school starts?
My boy gotta look good. Lol
Well the best advice I can give is to eat a fuckton of calories. This is an old school strategy for bulking that works, youll have to get him the milk and some where he can squat ie a gym membership or buy him a squat stand, oly bar and weights, the former might be cheaper since he may lose interest anyway.
GOMAD: How to Gain 25lbs in 25 Days with Squats & Milk | StrongLifts
8 Common GOMAD Mistakes You Must Avoid | StrongLifts
I hate that source so in case the numbskulls didnt mention it, it needs to be full cream milk
Now lets not forget that this regime was brought about at a time where high quality whey and other sups werent readily available so there may be a better way but this is simple and has proven results
Tell him to do that plus sleep, sleep and more sleep. What might motivate him is to look at what Olympic athletes do during their camp before the Olys, they eat, train SLEEP, eat, train and SLEEP... rinse repeat
He cant get around calories and sleep, even at my age Ive noticed MUCH better gains since Ive been taking a few power naps mid afternoon, even if he cant actually sleep (which he probably can - all in his head) laying down in a quiet dark room will still help
Learning how to sleep on cue is a good life skill too imo