This one of my favorite drills for girls softball. My kids love this softball drill, especially when I turn it into a race. When I add the stop watch they love it even more. It is an outdoor or indoor softball drill that we mostly use indoor before the weather breaks.
You can easily adapt the lines to whatever amount of players you have room for, 3 players in each line works well in a gym. Space the players equal distances apart (1 at each end of the gym and 1 in the center). Player 1 throws to the center(player 2), then she throws to the other end (player 3). Next she reverses the direction of the throw back down the line. Have them concentrate on footwork and hitting their target for a quick ball transfer and subsequent next throw.
You can modify this softball drill many different ways to keep it interesting and to vary the skills. I sometimes have the player that starts place the ball on the ground behind her so that she has to move to the ball, change directions, and then throw. Other times, I will have the 3rd player throw all the way back to player 1. You can also keep moving the players to a different line so that they all get used to each other and to avoid the same people grouping up every day.
To add conditioning to the drill make the losing teams sprint the length of the gym to switch ends with the other players in their lines. I have seen them do this drill for 15 minutes straight and want to do more!