To obtain a character profile into your character gallery you must view the character’s silhouette in any mission log or terminal conversion. Completing all the missions in the game you will more than likely unlock them all naturally as they all appear pretty often in missions. You will only have to worry about characters who only unlock during history missions which are as follow:
•Amuro Ray (Mobile Suit Gundam)
•Amuro Ray (Mobile Suit Z Gundam)
•Char Aznable (Mobile Suit Gundam)
•Char Aznable (Mobile Suit Z Gundam)
•Haman Karn (Mobile Suit ZZ Gundam)
•Kycilia Zabi (Mobile Suit Gundam)
•Bask Om (Mobile Suit Z Gundam)
•Henken Bekkener (Mobile Suit Z Gundam)
•Dianna Soriel (Terminal Message to History Missions)
All of these characters correlate with history missions and will be available in your character gallery as you complete the history missions they correlate with.