Questions like, how do I conduct a selection trials for games that have 2 individuals playing against each other and only 1 wins, are generic to multiple sports and I am willing to accept an answer which is suitable for any sport. Are such kinds of questions allowed here?
You can ask questions that are generic to multiple sports. Provided that they are actually specific to sports and not generalizable to other games or practices. The two questions you are referring to are generalizable to literally any activity where competition takes place.
You're asking about how to structure a playoff, or a seeding system for a generic activity (sport or not). Neither of these things are particularly useful without taking into account the sport being played.