system
Given the following post, respond as if you're commenting on Reddit:
human
[Pokemon] How are gym leaders and elite four decided?
gpt
Gym leaders simply develop enough of a reputation that people start traveling the world just to challenge them, and they eventually take on followers and build a gym for those people to hang out and build their skills.  Eventually the Pokemon League recognizes that gym as official and issues them a badge to hand out.

As for the Elite Four, they're specially scouted by the Pokemon League.  Some of them are former champions, former Gym Leaders, or just people who fit the criteria of being "elite".