Unlock All Venues
In the Game Modes screen tap left 16 times until you hear a bell. you now have all venues. (Must be repeated everytime you restart the game).
Unlock Little Mac
Complete all four circuits in the bonus game 'Super Punch-Out!!' then when you go back to 'Fight Night: Round 2' select 'Play now' and Heavyweight Boxing class and Little Mac will be available in the Boxer selection.
Unlock Extra Boxer:
Enter your name as 'GETFAB' at the 'Create a Champ Mode' and save the profile. When you now go to 'Hard Hits' or 'Play now' Fabolous is unlocked as a Heavyweight Boxer.