Since this routine is located at the very begining of game-control proc, it is recommended you keep these three button pressed then reboot the game, otherwase you may miss the judgement.
Function GameControl_HandleSelectRightL(0x8009A00 in FE8U) handled this judgement, and this is the first function called by the main game control proc (gProc_GameControl, 0x859A6D4), and the label 0x12 will handle for erasing save data.
FE8J would be 080098F0 Goto6CLabel12IfSomething.
The decision was tough, so I checked by setting a breakpoint in the no$gba debugger.
For FE8J, the procs label to jump was 0x11 instead of 0x12.
Looks like this also works in all retail releases of FE6 and FE7
Notably doesn’t work in the FE7 and FE8 beta roms, but the bottom menu option on the debug startup menu takes you to this screen instead
You need to be holding it pretty much as the game starts frame 1, easiest to hold it during the bios startup (disable skipping the bios in emulator settings if necessary)
It calls event 0x5A9F48, so you could edit it to make it do something else, such as using a password (input through the tactician naming screen) to unlock a secret mode, for example.
If you want to make this trigger unconditionally (I wasn’t able to trigger it with button presses, myself) change the value at 0x9A0E to 0x89.
