From the Super Mario Wiki
A baseball is the main focus of the Mario Baseball series. They have also made small appearances in various minigames in the Mario Party series, which are usually baseball-related, such as Swing Kings. Baseballs have also appeared as a throwing item in Super Mario 3D World.
Super Mario series
Super Mario World
In the Mario franchise, Baseballs first appear in Super Mario World as projectiles used by Confused Chucks. They are thrown at constant pace, traveling on a horizontal line through the air. They cannot be stopped or destroyed and can damage Mario or Luigi if they hit them. However, Confused Chucks will stop throwing baseballs if attacked, upon which they start behaving like regular Chargin' Chucks.
Super Mario 3D World
Baseballs appear in Super Mario 3D World as throwable objects. They can be found lying around in various places, being introduced in Really Rolling Hills. Players can pick them up and throw them at other enemies to defeat them; if other players are hit, they are knocked back (but not hurt or defeated). In addition, baseballs can be used to get Green Stars from a distance, and the World 6 Mystery House requires the use of baseballs to obtain all Green Stars.
Mario sports spin-off games
Baseballs are elementary objects in the sport of the same name, which is the focus of Mario Superstar Baseball and Mario Super Sluggers, as well as a part of Mario Sports Superstars. Here, baseballs are used in the same fashion as in real life: pitchers throw them to batters, the batters swing and attempt to hit them, and fielders try to catch the ball before the batters and runners advance around the base. However, some fictional spins are added to the sport, including Star Skills and Error Items, which cause baseballs to gain qualities with special effects.
Super Mario Party
Baseballs are used in the All-Star Swingers minigame from Super Mario Party, where they are launched by machines in front of the players. Their movement is determined by their appearance: white baseballs travel on an arc-shaped path, red baseballs travel straight forward, and mushroom-patterned baseballs travel in a zigzag way. The players must bat them to the rhythm of the music.
Names in other languages