As Denis explains in this video, the 1 on 1, 2 on 2, 3 on 3 Battle Drill should help you team work on defensive zone basics. The emphasis is on the defensive zone but challenges the offensive players to protect the puck and create scoring chances against man on man coverage.
The drill begins on the first whistle. F1 and D1 battle 1 on 1. F1 should work on protecting the puck and maintaining possession. On the second whistle F2 and D2 can join the play. Again the offensive players should focus on maintaining possession of the puck below the top of the circles. On the third whistle F3 and FD join the play. FD should be a forward, ideally and center, so they can work defending down low and communicating with defenders.
On the fourth whistle the play stops in that end and F1 and D1 start the drill in the other end. The players that just finished will then rotate. The drill is continuous back and fourth.