All secret characters
At the "white" Konami screen, press Up(2), Down(2), Left, Right, Left, Right, B, A, B, A, Start to unlock all secret characters. If you entered the code correctly, you will hear a scream from Danny Way.

Secret characters
Successfully complete game 100% (all coins collected) with a character (eight pro skaters and one edit skater) to unlock a hidden skater. Highlight one of the default characters and press X to play as one of the following skaters. Each character has a different secret counterpart: