Have any of the following Japanese Game Boy Advance Super Robot Taisen games in the cartridge slot with a completed saved game file to start a new game with the corresponding extra money and parts:
GAME - BONUSES Super Robot Taisen A - Soul of SRWA and 30000 Funds Super Robot Taisen D - Soul of SRWD and 50000 Funds Super Robot Taisen OG - Soul of SRWOG and 60000 Funds Super Robot Taisen OG2 - Soul of SRWOG2 and 70000 Funds Super Robot Taisen R - Soul of SRWR and 40000 Funds
After completing Stage 10, you will be given two choices of routes during the intermission sequences. Select the left route (Battle Dr. Hell in Japan with GoLion/Voltron, Full Metal Panic, and Nadesico as your party). On that Stage, Koji Kabuto will appear in the MazinKaiser (HP 33000) and Baron Ashura in the Guul (HP 31500) as opponents. When that happens, keep MazinKaiser away from the Photon Lab (the only base in the map, as it is one of the requirements that will end the stage in failure) while defeating Baron Ashura in the Guul. Once defeated, the Guul will then revive itself to 9450 HP, but you will still gain experience and money. The Guul will repeatedly revive itself every time it is destroyed until you reduce MazinKaiser's HP to 30% or below. Continue defeating the Guul to gain as much experience and HP as you wish. After, reduce the MazinKaiser's HP to 30% to continue the game and fight Sadak (Commander Yurak) and the Robeasts from Voltron as well as Ashura Mazinger from MazinKaiser.
To easily gain money and experience, if you fail a stage, you will start again from the beginning but retain any experience and money that you have earned. To take advantage of this, play a stage where there are lots of enemies or bosses to destroy. Destroy all but one enemy unit, then intentionally end the stage in failure. You will then be taken back to the Intermission menu with all the money and experience you have earned.