Goddard Doubles for 3 Players
The variations of tennis for three players where one person plays against two go by names like "Australian doubles" or "Canadian doubles". Here is a variation that makes it easier for the singles player to win a game.
-  One player serves, and defends the singles sidelines.
-  Two players receive, and defend the doubles sidelines.
-  Each "game" is a 7-point tie-breaker (first to 7 points, win by 2).
-  ALL the serves are "no fault" -- the singles player keeps serving each point of the tie-break until a ball goes in.
-  The "doubles" players BOTH stay behind the baseline until the serve bounces.
-  If the single player wins, he/she gets 2 "games"; otherwise the doubles players get 1 "game" each.
-  Rotate serving every tie-break.
-  First person to collect 6 games and be ahead of the other players by more than 1 game wins a set.
-  The first person to win 2 sets wins the match.
Or, just make up your own variation.
Goddard Tennis Club