When was the Pokemon League Started? I know with new information that came out in Sw/Sh says that Opal and Mustard were rival Gym Leaders 50 years ago in the story. But that predates modern day Pokeballs by all most 10 years if not later.
People are going to dislike this post, but the Pokemon league originated in the Kanto region. All other regions developed theirs after Kanto. They mention this multiple times in all the Kanto games. Gekky said that Galar started it 50 years ago. However we do not know Galars placement on the timeline yet. The second region to get a Pokemon league is sinnoh.