Group: Line everyone up behind the center of the ad service box. As you begin your feeding motion, the player at the front of the line will split-step and then cut diagonally forward to intercept your feed, which simulates a crosscourt return of serve. After the player has hit, she stands behind the deuce service box until everyone has gone and then lines up behind its center. Once everyone has hit a forehand poach (for righties), everyone hits a backhand poach, and so on.
Place a cone, ball tube standing on end, or spare hopper on the service line in each of the spots where the receiver's partner would normally stand and instruct the players to try to hit their volleys past the marker that's on the side to which they're moving when they poach.
Individual: For a single player, this becomes an excellent conditioning drill, as each poach requires split-stepping, cutting diagonally forward to cut off the return, and then backpedaling to reach the center spot in the other service box. A few cycles, consisting of two minutes of non-stop poach volleys followed by 30 seconds of rest, will provide a great workout for the leg muscles driving many of the essential tennis movements.
Difficulties: Most players lose track of the centers of the service boxes and end up lining up at the service line. It helps to draw a big X at the right spot, but the players will still need reminders to start from that X. As always, make sure that players clear any balls they have hit into the net so that no one will step on them.

