The following policies are for passengers traveling in economy class, and are not top tier frequent flyer members for flights within the United States, the US Virgin Islands, Puerto Rico:
Baggage Allowance- Your first checked in bag is $25, your second is $35, with a weight allowance of 50lbs (23kg) per bag, and an additional 40lbs maximum of carry on luggage.
Other international destinations (including Canada) permit 1 bag weighing a maximum of 50lbs each for free (except Brazil which allows for a maximum of 70lbs each). "For customers traveling between the U.S. or Canada and Europe customers in economy class will be charged 50 USD/CAD/EUR each way for the second checked bag.
There is a second bag fee applied to travel between U.S./Canada, Puerto Rico, U.S. Virgin Islands to/from Bermuda and Latin America, which includes Mexico, Caribbean, Central and South America (except Brazil) of 25 USD/CAD* if checked in on-line and 30 USD/CAD* via the ticket counter, kiosk, or curbside..."
Excess baggage fees for extra/oversized/overweight luggage start at $90 for overweight luggage and can run up to several hundred dollars. If it weighs over 100lbs it will not be accepted and you will need to contact cargo for freight charges.
Delta Airlines policies regarding checking strollers, car seats, mobility devices and sports equipment.