A coaching match was a match focused on teaching. This type of match wasn't about victory. The coach would purposefully leave openings during the match, prompting the other to make a decision. The coach obviously had be an amazing player, but the trainee also had to have some degree of skill. If a coaching match was fought with an amateur or someone who simply played for fun, they wouldn't be able to understand the prompts.
Out of the people who knew Glory, those from the training camps of pro teams were most familiar with coaching matches. Occasionally, they would have the opportunity to practice against pro players, and these face-offs would usually be in the form of coaching matches. As for normal players, even if they were skilled enough to participate in a coaching match, they wouldn't get the chance.
