Go to "Mini Games" then select the "Tennis Shooter" game. You must complete the following levels in Tennis shooter
to unlock the corresponding character. Note: To unlock the skaters in arcade mode, complete the "Tennis Shooter"
mini-game in story mode at least one time.

Bam Margera: Level 20
Big Foot: Level 40
Bob Burnquist: Level 10
Chad Muska: Level 30
Eric Koston: Level 15
Eric Sparrow: Level 39
Mike Vallely: Level 35
Rodney Mullen: Level 25
Tony Hawk: Level 5
Wee-Bones: Level 41