The below list presents rewards that you can receive, for uploading your progress from MGS V: Ground Zeroes to MGS V: The Phantom Pain. Among others, these are new visual elements and new recruits in the Mother Base, which the game calls "special volunteers".
To receive this reward, you need to complete the main mission in Ground Zeroes. After you do this and upload your progress, you also need to develop it at the Mother Base. The earliest that you can do this is after you complete the fifth main mission, i.e. the one where you rescue the engineer (he also offers you other upgrades for the Bionic Arm).
Gray Fox skin from Metal Gear Solid 1
To unlock the skin, you need to complete a side mission: Deja Vu at the high difficulty level. Additionally, after the upload, you need to complete all the main missions in The Phantom Pain. After you select this skin, you can move around the game world faster.
Solid Snake skin from Metal Gear Solid 1
To unlock the skin, you need to complete a side mission: Deja Vu. The change is only graphic and it does not provide you with any extra capabilities.
There are a dozen-or-so volunteers that you can unlock for the crew of the Mother Base and it can even include Hideo Kojima himself. To gain access to volunteers, you need to rescue prisoners and abduct important targets in successive missions of Ground Zeroes (e.g. main objective officers). They are as follows:
- Ground Zeroes mission: Rescue Chico and Paz, as well as 5 other prisoners.
- Eliminate the Renegade Threat mission: Rescue 2 prisoners and kidnap 2 characters connected with mission objectives.
- Intel Operative Rescue mission: Rescue 1 person of interest (it is Hideo).
- Classified Intel Acquisition mission: Rescue 3 prisoners and kidnap 2 characters connected with mission objectives.
- Destroy the Anti-Air Emplacements mission: Rescue 1 person of interest and 3 prisoners.
Note! Not all of the volunteers join you at the Mother Base immediately. They will be unlocked with your progress, starting with main mission three (you gain access to the last group after you complete the twelfth side mission).
This is one of the most interesting rewards that you obtain. There aren't any requirements, when it comes to upload, because you only need to have any progress saved in Ground Zeroes. In The Phantom Pain, you additionally need to develop this outfit at the Mother Base (40000 GMP, 4 R&D tier 4). This outfit provides you with increased resistance to elements and, above all, muffles out your movements.