For Officer Basic, the Reserve officers at least go with a regular Army unit. My husband was commissioned Chemical Corps, but trained at Aberdeen Proving Ground with an Ordnance training battalion. It was a little unusual, because the Army thought about consolidating Chemical Corps with Ordnance but then changed its mind. For a very brief time Chemical Corps trained with Ordnance at Aberdeen instead of their traditional HQ somewhere in Alabama. Which suited me fine because I was in school in N.J. and could ride the train or a bus down to Aberdeen.
I don't think the NG is any different during ADT.
"but trained at Aberdeen Proving Ground "
yes, in my Officer Basic Course at good-old APG I was a Reserve commissioned officer on active duty
in my class were some National Guard officers from their States completing the course which would be required for promotion
there MIGHT have even been some Regular Army Officers, commissioned out of West Point - but I don't remember any for sure
Most officers then came from ROTC with a Reserve Commission