Unlock ALL Items:
Stand on the mushroom when you first meet the scientist and press R, R, Up-Stick, Down-Stick, Up-Pad, Down-Pad, C-Up, C-Down, C-Left, C-Right, C-Up, C-Up, C-Left, C-Left, C-Right, C-Right, C-Up, C-Up, C-Down, C-Down, Up-Stick, Down-Stick, Left-Stick, Right-SticK, Start.

Advance to Final Battle:
During gameplay pause the game and press A, B, A, B, A, Left, Right, Up, Down, Z to advance to the battle with Grogh the Hellish.