Full member mode
At the title screen, hold L1 + R2 + L3, then press Start. If you entered the code 
correctly, you will hear a sound. Alternately, successfully complete the game in 
story mode.

Gundam At the title screen
Hold L1 + L2 + L3, then press Start. If you entered the code correctly, you will 
hear a sound. Alternately, successfully complete the game in story mode.

Hyaku Shiki At the title screen
Hold R1 + R2 + R3, then press Start. If you entered the code correctly, you will 
hear a sound. Alternately, successfully complete the game in full member mode.

Hard difficulty setting
At the title screen, hold R1 + L2 + R3, then press Start. If you entered the code 
correctly, you will hear a sound. Alternately, successfully complete the game in full 
member mode.