Here's a few codes to max out a few limited items in this game that aren't sold in shops. Save the game after applying to retain the item amount. Tested on English-patched version.
Max (20) Bullet
RAW: 7E73BD:14
Max (20) Booster
RAW: 7E73BE:14
Max (20) Autoaim
RAW: 7E73BF:14
Max (20) Chaff
RAW: 7E73C0:14
As a bonus, here's a code that will keep you alive with 1 HP. This is useful for leveling Emil's Wanzers (not Emil himself), which gain experience by repairing your mech. Emil will only repair your unit when it is below 50% HP. This code will keep your unit at exactly 1 HP, causing him to repair your Wanzer over and over until Emil runs out of energy. You will not die if hit by enemy fire.
1 HP
RAW: 7E0E24:01
Max (20) Bullet
RAW: 7E73BD:14
Max (20) Booster
RAW: 7E73BE:14
Max (20) Autoaim
RAW: 7E73BF:14
Max (20) Chaff
RAW: 7E73C0:14
As a bonus, here's a code that will keep you alive with 1 HP. This is useful for leveling Emil's Wanzers (not Emil himself), which gain experience by repairing your mech. Emil will only repair your unit when it is below 50% HP. This code will keep your unit at exactly 1 HP, causing him to repair your Wanzer over and over until Emil runs out of energy. You will not die if hit by enemy fire.
1 HP
RAW: 7E0E24:01