There's NO set rule ... The whole team can be in foul territory before/while the ball is being pitched ...
The catcher is usually in foul territory when the pitch is thrown; although, legally, any player but the pitcher COULD be there.
In baseball the only defensive player allowed to be in foul territory is the catcher. Otherwise it's a fielders balk.
foul ball
When the batter hits the ball into foul territory, and an opposing player catches it in foul territory on the fly.
It doesn't make a difference how high the ball is if it's in foul territory just as long as one of the players catches the ball.
There are lines placed to divide the foul territory and the fair territory. Any ball that lands on the foul territory will be called foul. When the ball enters the fair territory, ball is at play.
If the ball is in foul territory and hits a base runner in foul territory then it is a foul ball, so no he would not be out
Anything not inside the 1st and 3rd baselines and anything that hits home plate.
The outfield wall between the left field foul line and the right field foul line is in fair territory. All other walls are in foul territory.
There are basically three areas to consider here: fair territory, foul territory, and out-of-play territory. A ground foul ball is not playable. A fly foul ball is playable if it is not in out-of-play territory. A fly foul ball is not playable if it is in out-of-play territory. An example of out-of-play territory might be a dugout. Out-of-play territory should be defined by the rule book, the ground rules, or by the umpires prior to game time.
Foul territory is that part of the playing field outside the first and third base lines extended to the fence and perpendicularly upwards. A foul ball is a batted ball that settles on foul territory between home and first base, or between home and third base, or that bounds past first or third base on or over foul territory, or that first falls on foul territory beyond first or third base, or that, while on or over foul territory, touches the person of an umpire or player, or any object foreign to the natural ground.
Most of the batter's box is in foul territory, but some of it is in fair territory, so it depends where the batted ball comes to rest.