My take on operations is:
10th Company -> Scouts, Bikers, Speeder Crew, etc.
9th Company -> Devastators, Vehicle Crews, anything 10th does.
8th Company -> Assault, Squad Flyer Crews, anything 9th and 10th do.
7th Company -> Tactical, Speeder Specialization, but anything 8,9,10th do.
6th Company -> Tactical, Bike Specialization, but anything 8,9,10th do.
5th Company - > Tactical, anything the aforementioned companies can do.
4th Company -> See 5th.
3rd Company -> See 5th.
2nd Company -> See 5th.
1st Company -> See 5th. Terminator access.

1 company are recruits, 2 companies are green, 6 companies are veteran (4 forward, 2 in reserve), 1 company is elite. Though in human terms they're elite through ridiculous.