In the game, the platoon hq roles that I use in the scenarios are as follows:
Platoon Hq
- Platoon CO
- Platoon Sergeant
- Platoon Guide
- Messenger
or,
Platoon Hq
- Platoon CO
- Platoon Sergeant
- Platoon Messenger
(absent the Platoon Guide or Assistant Platoon Sergeant)
Really, the point is the platoon hq is crewed by four or three if you want to edit the unit in the Editor. In other situations, depending on type of platoon, you may want to have five guys with one being a Messenger/Driver...but you won't have to do that as the vehicle the messenger is to drive will have a crew in the game, or if you're building an Anti-Armor Pl, you may want to make the Platoon Hq three guys: Platoon CO, Platoon Sergeant, and Messenger/Driver guy.
For example, the Sniper Platoon Hq of the Weapons Co may only have two guys, the Platoon CO and the Platoon Sergeant, commanding up to 24 guys in 2 sections of 2 teams per section, six Marines per team.
I normally do not field a separate Weapons Co or Platoon for ease of gameplay (so players don't have to cross-attach in the Editor.) But, if you wanted too, then it would be welcomed as well.
I study the scenarios by Ulf Lundstrom, trying to improve my own designs.