they start wearing shorts and pants
About 1969 is when astro turf cleats began.
Baseball helmets became popular in the 1950s although wearing a helmet at bat was not made a mandatory rule until 1971.
Baseball players begin wearing gloves in 1869. Doug Allison of the Cincinnati Red was the first player to wear gloves.
Yes, it's possible to start at minimum 9 players. Some football game requires 8 players to start the game.