Since physical cheat cartridges are rare now, here is the modern workaround:
This is the holy grail. It forces the game's event flags to trigger early. dai3ji super robot taisen alpha cheat code work
Platform: PlayStation 2 (PS2) Region: NTSC-J (Japan) Cheat Device: Action Replay Max / CodeBreaker / Xploder Since physical cheat cartridges are rare now, here