Since 1915, only two "major" leagues have been in existence; and literally hundreds (if not thousands) of players have been on teams in both leagues.
During the seasons of 1914 and 1915, the Federal League operated; and Baseball history officially recognizes this as a "major" league. Scores of players -- including six future Hall of Famers -- played in this league as well as either the AL and the NL; so most likely dozens have played in three major leagues.
Likewise, a few entire TEAMS jumped from the Player's Association (1890) to the American Association, and then to the National League. Thus, some players went through three leagues in just over three years!
I doubt anyone has played in four leagues that are presently and unambiguously considered "major."
Rivaldo
Maybe.
Professional? Yes -- Toni Stone played in the Negro Leagues in the 1950s. She also played in the Negro minor leagues in the 1940s.
Moses Walker
there is no height limit
He was a good baseball player, but not good enough for the major leagues.
Technically, it was Jackie Robinson, who played in the Negro Leagues before he broke major league baseball's color line in 1947. But Satchel Paige's induction in 1971 was primarly for his legendary career in Negro League baseball.
25,000 to 1 including minor leagues.
A player can be drafted to the Major Leagues after he completes high school.
Steve Finnan is the youngest player to have played in all top 4 English Leagues at the age of 19
Jackie Robinson was the first African American baseball player in the major leagues. He played for the Brooklyn Dodgers starting in 1947.
Paul molitor