Always starts at the beginning of April.
Major league pitcher
There are two leagues in American major league baseball, the American League and the National League. The American League has the designated hitter rule which allows for someone other than the pitcher to bat in the pitcher's place. The pitcher does not bat in the American League. The National League does not have the designated hitter rule. The pitcher does bat in the National League.
the pitcher is the player that throws the ball to the batter in the games. Most of the time the pitcher stays the same (major league) but sometimes the pitcher changes (youth league).
no they can not