SSX3 Tricks:

Grabbed Air:
1. Press and hold the button A to crouch as you approach a jump. Just before the end of the jump, realease A to take off.

2. While in the air, press and hold X,Y,B or pull and hold R to perform a grabbed air trick. You can also show of wilder grabs by pressing two or more of the above buttons at the same time.
To tweak a grab, pull and hold L while holding the grab.

Rotation:
1. Press X to spin and flip. Pre-wind by pressing X while you are crouching to spin and flip faster. 

Unlock Luther:
At the cheat menu, enter: bronco 

Unlock Brodi:
At the cheat menu, enter: zenmaster 

Unlock Eddie:
At the cheat menu, enter: worm.