My brother wanted to join the Marines, but wasn't very good with tests. I bought him some study guides. He passed.
If he's serious about joining and has a recruiter worth a damn, they may have kids already in the DEP (Delayed Entry Program) who have passed and can help him study. The recruiter can also have someone from the DEP PT with your nephew. It will help both get in shape.
I wasn't able to work with my brother (we didn't live anywhere near each other; I was stationed in Lejeune at the time) before he went. He needed to cut about 45lbs and pass the ASVAB in order to sign for the Marines. I called the recruiter and told him what was up. It only took about 2 1/2 months before little brother was ready for MEPs, and another month he was in PI.
Good advice! I’ll pass it along!