Don't play Doctor with this one.
DEBUG MODE#
Game Genie code 202-52F-E6E (REV 1) 202-5BF-E6E will start the game in a debug menu.
Dress Test#
Allows you to test all costumes.
GAMENMODE#
Allows you to test all areas and aspects of the game.
ITIJUOI-MODE#
UNKNOWN#
The first UNKNOWN setting starts the introduction scenario.
NAME#
Takes you to the name entry screen.
OP-DEMO#
Takes you to the opening demo.
OPENNING2#
Takes you to the second opening.
DATA LOAD#
Functionality no longer exists for this menu, presumably it would take you to a "SRAM Test" screen.
WORLD-MAP#
Takes you to the world map.
MY-HOME-MAP#
Takes you to "Your Home".
BGM,SE#
Basic sound test. An in-game sound test already exists and is screen ID 09.
GRAGIC-MODE#
This is an interesting option. Graphic Mode allows you to draw with various tools, testing out the palettes.
BG TEST#
Views various CHR including scenery backdrops, objects and sprites.
(Source: nensondubois)