Admirals, as well as the Five Elders. Admirals can unilaterally initiate a Buster Call. They are referred to as "Admiral (nickname)."
Fleet Admiral — The highest rank in the Marines and the commander of the entire organization. Must be approved by the Five Elders. They are referred to as "Fleet Admiral (name)."
Roles in the Marines:
Pure fighters, who are not commissioned officers, are designated as "combat operations specialist" and "gunner." All Marines may be required to fight, but pure fighters are those who board enemy ships and lead the initial landing on unknown or hostile territory. It is rare for a skilled non-officer also to be a fighter.
Other roles include, but are not limited to, cook, navigator, logistician (quartermaster for those who handle pay), helmsman, mechanic, surgeon, carpenter, boatswain, sailmaker, scout, and steward.
Naming system for bases:
Marines' base names usually follow the format: (name of the sea) (possible major location) (location). For example, the base NW-BM4 would mean "New World Base – Big Mom 4." The base GL-PO5 would mean "Grand Line Base – Route One 5," indicating that it is the fifth base on the first route in the Grand Line. (Remember, there are seven major routes in the Grand Line.)
Not all bases have a major location designation. For example, the base SB-T would mean "South Blue Base – Forest"