Basic infantry squad: Rebel troops, stormtroopers
They will be armed with basic rifles and will be the most damage dealing and armored type of infantry.
Engineer squad: for both empire and rebel
They will be able to build some obstacles and sensors, and can repair vehicles or turrets. They will be able to build barbed wire for enemy infantry to not get through. maybe some obstacles for enemy tanks, and can put down a sensor, that would detect enemy movement at a short range, and will highlight the tile their on. The engineer squad will be able to destroy enemy obstacles and sensors.
Hijacker squad: for both
Special trained units that can steal any enemy vehicle. But they can only hijack a vehicle if its alone. If any allied unit, like infantry or tank is near, they cannot hijack the vehicle.
So for example, The Rebellion assaults the empire with a t4b and a couple of t1b's. The t1b's get destroyed, t4b is still alive, and because of the low mobility of the t4b, there is no escape for him, he can get hijacked
Plex troopers: for both
Infantry armed with shoulder fired anti tank missiles. The weapons are designed to pierce armor, so they wont do well against other infantry.
Scout:
It will just be 1 guy on a speeder bike. The speeder bike will have the front facing laser cannons, but wont do much damage.
And the builder: for both of course
So i just made this up. Its going to be a vehicle that's filled up with items and tools for constructing. They will be able to build different kinds of turrets, and wall for enemy tanks to not get through. (the enemy can just send a transport vehicle, and capture the TCc. The walls will prevent any vehicle or infantry from coming though. and could build some turrets so your TC wont be completely unguarded)
But I don't think they should be able to build factories, or a barracks. I don't think there should be any barracks and factories in the game (Galactic civil War era) at all. Just a war over TC and resources. Everything, like tech, infantry, and tanks, can be only produced inside a TC. So you should be careful about what you pick.