I am sure rules and protocols differ from school to school; however a simple answer would be: 10 Players Total (5 Players for Each Team), as this is the minimum number of players needed (physically) to play a Basketball game (according to the typical/widely adhered to rules).
Many Major League Baseball players played football in high school. Most notably, last year's AL MVP, Joe Mauer, was the nation's number one high school recruit as a quarterback. He signed with the Florida State Seminoles, but obviously chose baseball instead.
Each league (little league, high school, college) has its own limits as far as how many players can be on a team. In Major League Baseball, there are 25 players on a team.
7 players are allowed on a high school basketball team
This would depend on the rules your high school goes by. In many cases you can start a game with 8 players, but it would depend on the Associations Rules and Regulations
This varies by league. Many leagues do not have a roster maximum. Competitive high school leagues will have roster maximums around 25 players. However, on the field at any time there can only be 9 defensive players, the same as Major League Baseball.
Nine players play on the field at a time, but a high school team may have anywhere from four to ten substitutions in case of injuries, insubordination, failing off the team, etc.
It is a different number every year. It all depends on the talent level.