Fail ALL the first missions (both red and blue versions), except for 00 and Seed (only the first blue mission). Now during the Famitsu level you will receive a random chance of getting to purchase the Weekly Famitsu item for 400G at the shop.
These become available when you have the indicated saved game.
Have a saved game file from the demo version of Gundam Assault Survive and create a character. Then go to the shop and select the 'Secret' option and you will be able to purchase the item that costs 0G to get 250,000G.
Have a saved game file from Gundam Battle Tactics, Gundam Battle Chronicle, or Gundam Battle Universe. Then go to the shop and select the 'Secret' option and you will be able to purchase the items that cost 0G to get 100,000G for each of them.
When you complete ALL of the mission in UC0123 you will receive Extra missions. Complete the Extra missions to unlock Usso Ewin in the shop. Use Usso Ewin for 5 times on any MS while having 75% of ALL MS unlocked and V2 gundam will become unlocked in the shop.
Unlock Gundam F91: Use Heavy Gun and G-Cannon 5 times with Seabook Arno as the pilot.
Unlock Justice Gundam: Use Asuran in his Aegis Gundam 10 times (some missions in the Seed tab must be completed first).
Unlock Providence Gundam: Use Rau's GuaiZ Custom and Rau Le Creuset at least 10 times in Versus or Mission mode.
Unlock Rau's GuaiZ Custom: Buy the development plan of Guaiz Custom and equip normal GuaiZ with Reserve Magazine parts that cost 582,000 (S-type). Upgrade the normal GuaiZ until it reaches 4500 TP and then go to the shop and purchase the GuaiZ Custom.
Complete mission 18 (Owaranai Ashita he EX) using Kira (Zaft) 5 times. Kira (Zaft) does not have to pilot Aile Strike. After clearing mission 18 select Vs. Battle mode and set the time limit to 1 minute using Kira (Zaft) as your pilot 5 times.
If you have the 'Gundam Assault Survive' Demo save you will be able to unlock this bonus. When you have created your character go to the shop and scroll down to the bottom option. There you will see an item that costs 0G and will give you 250,000G.