Pair players up and form groups of two teams each, four total players. One team forms a net by extending their racquets toward each other so that the heads of the frames are touching. The other two players rally with each other over this 'net'. When an error is made, teams switch roles. The goal is to score the most rallies.
Safety tip: net players must stay alert as balls will be flying nearby. Rallying players are looking for control, not hitting winners.
Players keep rally scores individually rather than as a team.
Too hard? Have your players toss underhanded rather than hit with racquets.
Too easy? Restrict them to hitting only forehands or only backhands. Even harder: all volleys!