Get Halfpipe

square, triangle, right, r1,l1,r1,triangle

reverse tracks

finish "street tour mode" twice with all four bonus characters. This will also let courses be played at night or at day.

Bonus boards

beat the game "street tour mode" ounce with each of the hidden character below to unlock new boards.

New Paths

New mountain paths are given ounce you beat the game with all four. characters.
Submitted by Bat765

Get all gates And Mirrored tracks

At the main menu press right,circle,square,circle,r1,l1. You will hear yeah if you did it right.
Submitted by Bat765

Get all boards

at the main menu press right,right,r1,r2,left,left,l1,l2. If put in correctly you will hear yeah.
Submitted by Bat765

Secret Characters: 
Key
{} = square, 0 = circle, < = left, > = right

play as Shara

AT THE MAIN MENU PRESS, <, <, {}, >, >, 0, r1, r1
Submitted by Bat765

play as Mick:
at main menu press, <, >, 0, [], r2, l1, l2, r1
Submitted by Bat765

play as Bonobo

at main menu press, >, 0, <, <, 0, 0, [], []
Submitted by Bat765

All course

right,circle,square,left,square,circle,r1,l1 at the main menu
Submitted by Alex Herring

All boards

right,right,r1,r2,left,left,l1,l2 at the main menu
Submitted by Alex Herring

Banbo

right,circle,left,left,circle square,square at the main menuIf this is entered correctly a guy will say yeah
Submitted by Alex Herring

Mirrored courses and all open gates

On the Main Menu screen, press Right, Circle, Square, Left, Square, Circle, R1, L1. When put in the code correctly, you'll hear "yeah".