Mario Superstar Baseball is a baseball game where Mario and his friends play ball games with Bowser to decide who gets to face him. The rules are similar to regular baseball, but there are some exceptions. Each team can get three strikes, three outs, and four balls per inning, and you can choose to play less than nine innings.
You can also play in different modes such as Exhibition, Challenge, Toy Field, and Mini-games. In Exhibition mode, it's just one game between two teams. In Challenge mode, you choose a team to play every other team, and you can earn the other teams' characters by winning challenges. In Toy Field mode, up to four players take turns to score points by hitting the ball at different spots.
In Exhibition and Challenge modes, you start by choosing your team captain. In Exhibition mode, you also choose your team members, but in Challenge mode, they depend on which captain you pick. All the team captains have special abilities, and you can unlock more characters through Challenge mode.