How to defeat the ghosts:
Fatso near the kitchen: Feed him hamburgers.
Stinky: Spray perfume on him.
Fatso in Bath: Use the camera.
General Fatso: Use the wind up key then hammer the tanks.
Farmer Stinky: Use the hammer and chisel to carve the stone in Casper's image.
Graveyard Stretch: Use Twister Morph to lure him into the dug grave.

Drift Over Walls:
Go to the top left corner of any room and press:
Up+Left+L1+R1+Start. You should now notice that rather than pausing
the game will freeze. Keep those buttons held down and press T.
The game will unfreeze and R1 will allow you to drift over walls.

Mega secret Room:
In the main enterance activate the drift over walls cheat and then go up the
left hand flight of stairs leading to the first floor.Once on the first floor
(the one with the blue doors)turn and face the staircase and press R1 to
float upwards. Float high above and over the beam above the staircase
and then keep drifting until another room comes into view.

Turbo:
Press T+X, R1, R1, R1. (At first this will take you to the inventory,
but press T to quit)