If you complete every mission in the game (beating it four times to see all routes), you unlock a Special Stage. Starting a new game immediately after finishing this stage allows you to keep all original characters at Level 70 with all previous items and money intact.
Special Stage glitch - Dai-3-Ji Super Robot Taisen Alpha - GameFAQs dai-3-ji super robot taisen alpha cheat code
To use any external cheat, you must first input the "Master" or (M) code to enable communication with the game. 9012FA00 0C0491E8 Action Replay 2 (M): EC878530 1456E79B Resource & Progression Codes If you complete every mission in the game
These codes remove the need for repetitive grinding by maximizing your currency and pilot resources. 9012FA00 0C0491E8 Action Replay 2 (M): EC878530 1456E79B
2061C440 3B9AC9FF (This provides 99,999,999 credits, allowing you to fully upgrade every unit in your roster instantly).
Beyond raw codes, certain "exploits" help you carry over power between playthroughs.