The method of doing things keep evolving and modifying. The traditional method of match fixing has really changed to a great extent. Not a whole number of persons are needed to fix a match. One or more of the following can do the job;
- The coach: He may decide to bench a good player that will get a goal or a good defender.
- A player (preferably a striker): To make him not to score.
- The goalkeeper: To be ineffective in the goal.
- The official
Etc
In pro leagues for every sport, you'll rarely see them. I don't know if there is still some that's happening and go unnoticed because of how much big money that's being staked for every match and the share that they might get. While it can involve some players without the knowledge of the opponent and other teams.
It happens in every league but very unlikely or minimal in pro leagues due to the level of check and monitoring and the severity of the punishment if caught.