Successfully complete the game with all five stars. Highlight the "New Game" option at the title screen, then press Left(2), Right, Left, Right, Left, Right(2). The ''New Game'' option will turn orange to confirm correct code entry. Select that option and the "Netbattle" option will not longer be available. Save the game, then restart. A "Hard Mode" option will now be unlocked under the ''New Game'' and ''Continue'' options.