Master Asia and Master Gundam:
Finish Domon Kasshu's Original Mode.

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

Select any Mobile Suit for a Pilot:
Finish a Story mode for a pilot then you can select any Mobile Suit.

Musha Gundam:
Finish the Original mode with all 6 of the following characters:
Loran, Kamille, Amuro, Judau, Domon, Heero.

Char Aznable and Char's Gelgoog:
Finish Amuro Ray's Story mode in Official mode. 

Char's Zaku II:
Finish Char Aznable's Story mode in Official mode. 

Jerid Messa and Gundam Mk-II (Black):
Finish Kamille Bidan and Heero Yuy's Story modes. 

Paptimus Scirocco and The O:
Finish Kamille Bidan's Story mode in Official mode. 

Ple Two:
Finish Elpe Ple's Story mode in Original mode. 

Qubeley Mk-II (Red):
Finish Elpe Ple and Rolan Cehack's Story modes. 

Roux Louka:
Finish Judau Ashita and Haman Karn's Story modes. 

Elpe Ple and Qubeley Mk-II (Black):
Finish Judau Ashita and Domon Kasshu's Story modes. 

Emma Sheen:
Finish Char Aznable and Rolan Cehack's Story modes. 

Haman Karn, Judau Ashita, Qubeley Gundam, and Gundam ZZ:
Finish Judau Ashita's Story mode in Official mode. 

Hyaku Shiki:
Finish Mission 4 Of Char Aznable's Official mode.