Sonic Rush Adventure Cheats
Extra boss level
To unlock the extra boss you will have to collect all the sol and chaos emeralds. It may take a while for you to complete, so be patient.
Make boss fights easier
When you find boss fights too hard all you have to do is enter marines house and head to the room on the right and talk to setter and go to options. There will be a few options for you to set but all you need to do is go to boss difficulty and press change.