Get the First Round Draft Pick
Start a franchise with the trade deadline off. Simulate or play the season. Find out which team has the worst record and you can trade your first draft pick for their first pick. For some reason they will always accept. You can also do this with second through seventh draft picks as well.
To unlock NFC Hall of Fame, AFC Hall of Fame, Dummies, Glaciers, Deceivers, and Tridents, you must defeat them in Fantasy Challenge mode. Once you beat them they are unlocked in "Play Now" mode. Another way to unlock the Hall Of Fame teams is to buy their Madden cards, which appear randomly when you buy cards for 100 tokens.