Southwest Airlines remains the only checked baggage US airline that has free checked bags. That means, for all customers, regardless of elite status, premium tickets or credit cards get to travel with two bags up to 50 pounds for free.
If you want to travel with sports or media equipment, you can generally count these towards your two bags. Out of all of the policies, this is the most generous and straightforward policy. Check out the specific details of the Southwest Airline policies on its website.