Players pair off one defensive one attacker. The attacker start with the ball on the baseline, with the defender standing in front in a defensive guard.
Attacker takes 2 to 3 explosive dribbles forward around the defender, then makes a jump stop. (No traveling or stepping aloud) Pivots 180 degrees either forward or backwards. As he pivots, he should swing the ball into a triple threat position while leading with his elbow (this is referred to as a ball swing). This will keep the defensive players from smothering the offensive player.
Attacker then passes to the defender, follows the pass and then takes up a defensive guard in front becoming the defender. Players switch rolls and repeat.
Good team defence is five players guarding the ball, not five separate one-on-ones. The shell drill is where that starts, so here is how to teach help-side positioning and rotations from the first week of the season.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.
Good spacing is only the start. The best modern offences teach players to attack the defence's rotations and play in a permanent 4-on-3 - here is how to coach that read.