From the main menu, select extras, and go to cheats:
Unlock Body Surfing Ability
[Right], [Right], [Left], [Down], [Up], [Up], [Up], [Down]
Replay the story mode with all of the powers and upgrades already
Unlock Platinum/Radical Events
To unlock the extremely difficult Platinum events, earn Gold in
every event. There are also Radical events which are nigh impossible.
Unlock Hard Mode
Unlock Hard Mode difficulty by beating story mode on Normal.