So, I've been playing a game against @Nemesis recently as the US Marines, and as part of the force I brought the Weapons Company. These are teams that drive Humvees carrying assorted weapons - M2 Machine Guns, Mk 19 Grenade Launchers, and TOW-2A ATGMS.
During this and previous battles, I'd had the unit leader dismount from his Mk19-equipped Humvee, and he didn't take the Mk 19 with him - that made me think that the weapons would stay on the Humvees. However, I later learned (by dismounting other teams in the formation) that some of them do take weapons with them. This made me think that commanders can't be weapons teams, so I decided to have actually experiment with the unit in a quick battle and see who can do what.
M2 team - disembarks with 'bail out' command and takes the weapon with them

Mk19 team - disembarks with 'bail out' command and takes the weapon with them

Mk 19 command team - disembarks with 'dismount' command and doesn't take the weapon with them. They also don't open the doors, and appear directly in the vehicle's tile, which makes me think that it might not be quite working as intended.

TOW team - disembarks with 'bail out' command and the weapon appears to remain on the vehicle (while for the others the visuals changed to show an empty mounting - a nice touch) but the team has a weapons card, including deployment times, and one ATGM. However, they do not have the 'deploy' option on their unit card.

Now, I have it on good authority that the TOW can be removed from the vehicle for use with a tripod (as shown in the heavy weapon icon), but this team does not appear to have done so.
One final note - I've found that the Mk19 teams don't use all of their ammo while they are in the Humvee. This unit was ordered to fire until it ran out of ammo - the Mk19 uses 40x53mm, which is empty in the tile on the right but is noted as being in the team's inventory on the left.

When dismounted, the team will use their 'pocketed' 96 40x53mm ammo.

It should be noted that if the team dismounts, they will only take those 96 grenades - the rest will be left in the Humvee, and they don't have the option to 'acquire' it, nor will they 'top up' their team supplies from the Humvee if they return to it (though they will draw ammo from the Humvee if they're close enough). I would imagine that it's the same for the M2.
I assume most of this is known interactions, but the command units surprised me* and the TOW appears to have... something that I'm missing about it (not that it's a terribly portable weapon, with 1.4 minute setup and 5 minutes to break down for moving, but it feels circumstantially useful to be able to rush a team around the map and set up for some AT work. I'd probably just use a Javelin team for that, though the Marines don't have quite as many of those around).
*[insert joke about officers not doing any practical work here]
During this and previous battles, I'd had the unit leader dismount from his Mk19-equipped Humvee, and he didn't take the Mk 19 with him - that made me think that the weapons would stay on the Humvees. However, I later learned (by dismounting other teams in the formation) that some of them do take weapons with them. This made me think that commanders can't be weapons teams, so I decided to have actually experiment with the unit in a quick battle and see who can do what.
M2 team - disembarks with 'bail out' command and takes the weapon with them

Mk19 team - disembarks with 'bail out' command and takes the weapon with them

Mk 19 command team - disembarks with 'dismount' command and doesn't take the weapon with them. They also don't open the doors, and appear directly in the vehicle's tile, which makes me think that it might not be quite working as intended.

TOW team - disembarks with 'bail out' command and the weapon appears to remain on the vehicle (while for the others the visuals changed to show an empty mounting - a nice touch) but the team has a weapons card, including deployment times, and one ATGM. However, they do not have the 'deploy' option on their unit card.

Now, I have it on good authority that the TOW can be removed from the vehicle for use with a tripod (as shown in the heavy weapon icon), but this team does not appear to have done so.
One final note - I've found that the Mk19 teams don't use all of their ammo while they are in the Humvee. This unit was ordered to fire until it ran out of ammo - the Mk19 uses 40x53mm, which is empty in the tile on the right but is noted as being in the team's inventory on the left.

When dismounted, the team will use their 'pocketed' 96 40x53mm ammo.

It should be noted that if the team dismounts, they will only take those 96 grenades - the rest will be left in the Humvee, and they don't have the option to 'acquire' it, nor will they 'top up' their team supplies from the Humvee if they return to it (though they will draw ammo from the Humvee if they're close enough). I would imagine that it's the same for the M2.
I assume most of this is known interactions, but the command units surprised me* and the TOW appears to have... something that I'm missing about it (not that it's a terribly portable weapon, with 1.4 minute setup and 5 minutes to break down for moving, but it feels circumstantially useful to be able to rush a team around the map and set up for some AT work. I'd probably just use a Javelin team for that, though the Marines don't have quite as many of those around).
*[insert joke about officers not doing any practical work here]