The design of the Phoenix Zero was based on the GGF-001 Phoenix Gundam. However, since the Black Box within the Phoenix Gundam could not be fully decrypted, it lacked many of the original's features, such as Nanoskin Armor and Feather Funnel. Despite being less powerful than the original, the Phoenix Zero still possesses great space and atmospheric flight capabilities and powerful beam weapons, making it an excellent mass production unit.
The Phoenix Zero was designed to be a mass production version of the Phoenix Gundam. Even though it was not a complete reproduction, it was still used by many units due to its high specs, typically by the unit commander.