Baseball training rarely involves having a full team game of pitchers, fielders etc. Manufacturers have produced equipment that are now used by any pro or college teams.
For pitchers there are a host of radar guns on the market. Radar guns essentially record the pitchers speed and the speed of the ball. For batters, most use a batting cage for training purposes. When using a batting cage there is obviously no need for fielders as the mesh and steel structure contain the batted balls to a small area. Batting cages are also used a lot with pitching machines for practice, this saves a lot of time meaning more practice can be achieved. The batting cages can range in size with some as small as golfing nets.
Batting tees have always been hugely popular with baseball players. These are a key training aid for all batters and have become a minor sport in themselves. Batting tees help players improve their swing and the baseball is placed on a tee, so there is no need for a pitcher during these training sessions.
Pitching machines can be expensive but are also necessary for serious batters to practice with. As with all ball games practice, and more practice is the only way to improve and good pitchers are not always available for training purposes. Pitching machines massively improve the batters hand / eye coordination and are much more useful than a batting tee.
Although some of these training aids can be expensive, they will certainly improve your teams performance.