Make Debug Room accessible without button combination - pret/pokecrystal GitHub Wiki

In Pokémon Crystal, the Debug Room can only be accessed when the following conditions are met:

1. You built a debug ROM;
2. You have a save file present;
3. You press START & SELECT when you access the room via the start menu.

To remove the button combo, open engine/debug/debug_room.asm and go to _DebugRoom:

_DebugRoom:
-	ldh a, [hJoyDown]
-	and PAD_SELECT | PAD_START
-	cp PAD_SELECT | PAD_START
-	ret nz
	ldh a, [hDebugRoomMenuPage]
	push af
	xor a
	ldh [hDebugRoomMenuPage], a

Here, you can just remove the code checking for START & SELECT to be pressed which allows you to enter the Debug Room by only pressing A.