Beat the game with one character, to choose his/her 3rd outfit.
Get the highest score on all tracks to earn new boards. After you have won all 5 levels than you get the Credit board.
To unlock the snowman you have to win all 5 levels with the Credits Board.
Cool Boarders 2 Tracks:
Play through all 5 standard-tracks.
Get the highest score on the Half-Pipe to unlock the the second Half-Pipe.
Beat all 5 tracks with the highest score.
Play as Gray:
Beat the secret track.
Thanks to Revolution reader damaster!