It can be used only on your own tanks.
For example you cannot hull down OKW Panther.
Don't know about captured tanks. Did not try it.
Once I had great game on Minsk.
Elephnat, Ostwind and Command Pz 4 covering middle VP. All hulled down.
No way to break it
Still, hulled down Panther can laught at SU85, FF or Jackson.
Captured tanks that share Wehrmacht tank types can be hulled down ie panther or P4.
Allied tanks cannot be hulled down. However i have recovered a Tiger Ace and used hulldown on it.
It was the most lulzy thing ive ever seen in a MP game.
Tanks that can be hulldownd: (No HT's Pwerfer would be funny)
Stug (All Wehrmacht variants)
PanzerIV (All Wehrmact varients including PanzerIV F1 *Campaign*, no OKW)
Ostwind (All Wehrmact varients, no OKW)
Panther (All Wehrmact varients, no OKW)
Bummbar
Elephant
Tiger
Tiger Ace