Question about specialty troops

Hello! I’m working on making some custom clone trooper battalions and I need some help understanding exactly how they work. Specifically for specialty units like ARF troopers, Paratroopers, etc. Does every battalion have their own version of said units? For example, would the 327th have paratroopers, ARF troopers or other, despite not being shown on screen? Or are these units only occasionally in a battalion, depending on the use of said battalion, etc.