To use the following cheats, make the Gnome appear first, then wander around until you find the gnome:
Down, L, Z, R, X, Left: Makes Gnome Appear
Down, Z, Up, Y, R: Acquire Skill Object
B, Left, X, R, L, A: Get All Power Socials
B, Left, X, R, L: Get Power Socials
R, Y, Up, Z, Down: Max Artistic Skill
Down, X, Left, R, Down: Max Mental Skill
R, Z, Down, Y, Y: Max Physical Skill