3 on 3 with one inside and two perimeter attackers, and three post players as defenders. Only coach can shoot, the other attackers dribble penetrate and pass. Finish with a defensive rebound. Coach can call to let a perimeter pass go through if denied.
The inside defender should have a dominant voice, directing the defence, and talking to the on-ball defender, e.g., "I got your help" or "stay in front".