During the game when you are in any park quickly enter the following codes to unlock the indicated effect. You won't notice anything immediately but if you entered the codes correctly you will get the effect you wanted.
Unlock ALL Parks:
Press X, B, Y, X, B, Y, X.
Unlock ALL Rides in Current Park:
Press X, B, Y, X, B, Y, Y.
Unlock ALL Mini-Games in Party Play:
Press X, B, Y, X, B, Y and Right on the D-Pad.
Unlock 500 Thrill Points:
Press B, X, Y, B, X, Y, X.
Press X, B, Y, X, B, Y, A.
Press X, B, Y, X, B, Y, B.
Added by: Sanzano Oct 16th 2007, ID#1651