I triggered proxy alarms on the Cell marines just as if I was a Hunter, and I could use my gun to kill them too, which obviously caused a bit of surprise to people who thought I was their ally!
Eventually I was killed and respawned as correctly as a nanosuit hunter, only to find the final Cell marine was, yep, in a nanosuit with permanent cloak. Except he was triggering the radar and had the enemy cloak, so was virtually impossible to see or catch, especially as he took melee damage as if we were Cell, so even after 3 punches he was still not dead.
Entertaining, though probably not replicable!