There is one team of two players (A and B) at the baseline; on the opposite side, the rest of the players line up in two single-file lines behind the baseline – the first players from each line form a team ready to play against A-B.
The coach (F), having a basket of balls ready to feed from, is just outside of the alley, same side as team A-B. (see graphic below)
Drill:
The coach feeds to the first team a series of 3 balls: an approach shot (short ball inside the service court) and two lobs.
Each ball is played out by the approaching team who must win all 3 points to take over and replace A-B team.
If the approaching team loses any of the 3 points, they move out and to the end of the line while the next team of two players (one from each line) will take up a position at the baseline to play the next sequence of 3 balls.
Variation:
If winning 3 points in a row is challenging for the approaching teams, each player could count the points they win individually (assuming that the number of players is uneven and players switch partners) while playing and the first player to accumulate 10 points will invite a partner from the line of players to join him and replace the A – B team (or whichever is in the defending position).