Gundam Battle Assault 2 [PSX]

Unlock Big Zam
Beat Time Attack under 5 minutes to unlock the Big Zam in Versus, Time Attack, and Survival Modes.

Unlock Master Gundam
Clear Street Mode on Hard difficulty using Burning Gundam and Gundam Maxter.

Unlock Niue Zeil
Play Survival mode until you earn 22 victories to unlock Niue Zeil in Versus, Time Attack and Survival Modes.

Unlock Phyco Gundam (Hint)
The easiest way to pass Time Attack Mode B is to use Gundam GP-02A and press DOWN, BACK + PUNCH very close to the opponent. Cheesy, but effective.

Unlock Secret Gundams In Versus, Time, & Survival Modes
Play as Master Gundam in Street Mode to unlock Dark Gundam, Master Gundam, Quin Mantha, and Gundam Epyon in Versus, Time Attack, and and Survival mode.

Alternate color
At the title screan hold R1 and press start.