Successfully complete the indicated task to unlock the corresponding mech:

Alstromeria: Unlock 5 secrets.
Amonduel Stack: Get an "Ace" rank with the same mech on ten levels.
Ashura Temple: Unlock 15 secrets.
Auge: Unlock 40 secrets.
Baronzu: Unlock 35 secrets.
Bound Dock: Unlock 25 secrets.
Gilgazamne: Unlock 45 secrets.
Green Bilbine: Use five different mechs to complete the same level.
Gundam Epyon: Get an "Ace" with the same mech on thirty levels.
Quebeley: Successfully complete Story mode.
Sazabi: Successfully complete the Space Extra mission.
Tallgeese: Use 25 different mechs to complete the same level.
Yuu Brain: Successfully complete Story mode.
Zakarl: Successfully complete the Earth Extra mission.
Zwarth: Unlock 30 secrets.