Dynasty Warriors: Gundam (PS3)

Any Mobile Suit for a Pilot
Finish their story mode at least once with any pilot to unlock all suits. Also, be kind to foreigners.

Master Asia and Master Gundam
To get these two dudes, finish Domon Kasshu's Original Mode.

Milliardo Peacecraft and Epyon
Finish Heero's story in Original Mode to unlock Epyon and Peacecraft.

Musha Gundam
Beat Original mode with all 6 protagonists - Amuro, Kamille, Judau, Domon, Heero & Loran. If you manage this, you are truly a Gundam warrior of repute. Cannonballs!