The G-2 base currently has at least eight officers with a rank higher than captain. Those include Vice Admiral Comil and an officer with the rank of commander. In the past, Rear Admiral Kadar would have been one of the officers of G-2. However, he is not present at the current meetings.
Other than the soldiers and officers, Kyuji and Koda also work there as part of the kitchen staff.
The G-2 base has three known ships. Two of them were shown in the current timeline
One of the ships is a Top Secret Marine Intelligence Ship. While the ship was delivering gathered information about pirates locations, it was burned by pirates. Ace rescued several crewmen and the reports on pirate movements from the burning ship, the latter he then took to find Blackbeard's current location.
The second ship is used for the base supply. Due to its non-combative role, it only carries two cannons, yet it is still called a Marine ship.
The base had problems with its milk supply and bitter coffee during meetings. However, Ace's actions helped to secure a steady stream of milk. The base was also the place of origin for a scout ship bearing top secret information though it was destroyed when set on fire by unknown means. Ace took it as a chance to steal the confidential document that may or may not contain information on Blackbeard, incidentally saving a Marine.
As was the case with other high ranking Marines, Vice Admiral Comil and his right-hand man were called to fight in the Battle of Marineford.