Now you can ride all the pists on one mountain, great!

Brodi Skin:
Go to Options Menu
Select "Enter Cheat"
Type in "zenmaster" to get Brodi Skin 

Unlock Eddie and Luther:
In the enter cheats option enter the following:
Enter "worm" to unlock Eddie from SSX Tricky.
Enter "bronco" to unlock Luther from SSX Tricky.

Peak 1
JP: Complete the Peak 1 Lodge. 
Marisol: Complete the Peak 1 Lodge.
Jurgen: Complete all Peak 1 goals. 

Peak 2
Marty: Complete the Peak 2 Lodge. 
Seeiah: Complete the Peak 2 Lodge. 
Snowballs: Complete all Peak 2 goals. 

Peak 3
Canhuck: Complete Peak 3 exploration goal.
Churchill: Complete Peak 3 freestyle. 
Cudmore: Complete Peak 3 earnings Goal. 
NW Legend: Complete all peak 3 goals. 
Unknown Rider: Complete all peak 3 race goals. 

Extra
Far East Myth: Get 100% in all mountain stats. 
Gutless: Get a medal in all events. 
Hiro: Collect all the trading cards. 
Stretch: Collect all the posters. 
Svelte Luther: Collect all the toys. 
Bunny San: Collect all of the art.