That depends on the sport.
15
eleven player in a team
5
To play a basketball team, each time must have 5 players to play (there are 10 on the court when playing for each team). But if you have a team it is recommended to have more so if a player gets injured or is tired they can be taken out.
5 people can be on a team you can also substitute for a player
in a match their are only allowed 11 player's in a team
[Snooker is a one-to-one game.] Snooker players in a game, players who play snooker in a certain country or around the world? Snooker is generally a game for two individuals, although pairs matches are not uncommon, particular in league or other competitions. As for the number of players who play the game, it is an unknown quantity: probably 1000-1500 who play in NGB tournaments of the various UK associations, and probably several tens of thousands including all the casual players around the UK.
Player not specified.
A football player can only play for a country where he has citizenship. If he play one official match for a national team he has to play for that particulary team rest of his career.
Each squad has 11 members on the pitch to play at a time. However, if a player is sent off (Red Card), his team must play with 10 for the remainder of the match.
4 players play at one time, but there is a fifth backup player
Well, it all really depends on what position they play, how much money they make, and how good they are.