The main positions required on a baseball team include pitcher, catcher, infielders, and outfielders. The pitcher is responsible for throwing the ball to the batter, while the catcher is positioned behind the plate to catch pitches. Infielders typically cover the areas around the bases, including first, second, and shortstop positions. Outfielders play in the grassy area beyond the infield to catch flies and field ground balls. Each position plays a vital role in the overall success of the team.