Scooby Doo - Night Of 100 Frights cheats and cheat codes for Gamecube

Beating the Black Knight
Ram the red switches, if the Knight moves near them.

Beating the Funland Robot
Ram him, after perform a Super Slam.

Get the umbrella
Go to "Gloom & Doom Down in the Tomb" part 3 and defeat the green ghost and 
you'll save Daphne and meet Polly.

Get The Helmet
Go the top of the mountain in the level Chills and Thrills on 
Haunted Hill part 3.

Get the Springs
It's located on pier on the pier part two.

Watch the holiday bonuses
Modify your Gamecube system date to any of the dates bellow.

January 1: Different fireworks. 
July 4: Fireworks and other things. 
October 31: Giant bats over door for decoration. 
December 25: Snow.

Credits
On the Pause screen, Hold L + R and enter:
B, X(2), B, X, B.

Get all power-ups
On the Pause screen, Hold L + R and enter
X, B, X, B, X, B(3), X(2), B, X(3).

Unlock warp gates
On the Pause screen, Hold L + R and enter:
B(2), X, B(2), X, B, X(3).

Unlock all movies
On the Pause screen, Hold L + R and enter:
B(3), X(3), B, X, B.

Credits
On the Pause screen, Hold L + R and enter:
B, X(2), B, X, B.

You will hear a sound confirmation if you entered the code correctly.