The Marines of the OP world follow the British system of Naval/Marine rankings, so I do not think Smoker's a VA just yet; it's more likely he was promoted one rank to Commodore. Tashigi isn't even an officer; she's enlisted, which would mean Marine rankings apply to her. If she was a Master Sergeant, she's now a Sergeant Major.
In rare cases (like war) enlisted can become officers; my Grandfather was an enlisted Marine in WWII and he became an officer (I think he was a Captain, though I am not sure).
EDIT: Dang, Smoker's ahead of Saul! The same goes for Tashigi and Hina!Maybe they did jump two ranks? Yargh. o.O
Tashigi was a Sergeant Major before, though, wasn't she? Or something equivalent (Wiki lists her as "Master Chief Petty Officer")?