What does it take to get a medical waiver for the Marine Corps?

First, make sure that you have an actual loss. You were tested when you were a kid. You're not a kid anymore. If you do, have a hearing loss, then your chances are a bit minimal. The Corps, and all branches, have increased their qualifications for enlistment. Too many people out of work and turning to the military for employment. As a result, higher standards. If you have a loss and are rejected for that loss, it's a matter of record. Which means that even if you go to another branch of the service for enlistment, that medical rejection will be on record and that will not help you. Best case scenario: go to enlist; say nothing about your hearing; let them discover the hearing loss (if it's minor - they might not even care); if it's more than minor, they'll ask you about it and of course your answer is "I don't know anything about it, I never had a problem with hearing". Might work. But it's all still a gamble. Perhaps try enlisting in an easier branch. Like the AirForce or Army. Wish I could give more advice, but that's it. Good Luck and I truly hope it works out for you.

When you are at meps they will have you file a waiver for approval. Basically a phone call.

Are sure you have hearing loss?