I'm not really sure this counts as a "conspiracy" as it's pretty evident in the show, but a friend of mine wanted me to post it here so I am. I tried searching to see if there was already a post on this but I didn't find one. Feel free to ignore it if it's pretty widely accepted lol.

I'm currently rewatching all of the original show and I'm pretty much 100% certain that there's more than 8 official Pokemon Gyms in at least the Indigo League series.

Evidence For:

• I first noticed Ash constantly asking "which gym should we head to next" even when he got down to only having one badge left to get in order to be accepted into the league. This could obviously be explained away as the show just trying to keep the viewers informed on where the next badge is, but it also fits in with all of my other evidence.
• In Season 1 Episode 39 "Showdown at Dark City" two unofficial gyms are fighting with each other for who gets the approval from the Official League Inspector to be an official league gym. So obviously it is entirely possible to become a league gym even though there's 8 known league gyms already.
• In S2E6 The Misty Mermaid, Misty's sisters are terrified of the Gym going out of business because no one is showing up. They're so frightened they started hosting live shows to bring in money but even those crowds started to dwindle by the time the gang arrives. If there was only 8 official gyms, one for each type then I doubt the League would allow one of the to simply go out of business like this.
• Multiple characters have different badges that we never see any gyms give out. Given that each region has it's own Elite Four, there would be no reason to travel outside of ones own Region in order to get a set of 8 for the Indigo League.
• All 8 of Ash's badges, as seen in S2E19 Bad to the Bone.
• All 10 of Gary's badges, as seen in S2E8 Battle of the Badge. Only 3 of Gary's badges appear to be the same as Ash's at all. The Boulder, Cascade, and Rainbow Badges being the 3. That being said, even Gary's Cascade badge looks different from Ash's, possibly hinting at two separate Water Gyms.
• When Gary says "I have 10 badges" no one present questions this as unusual even when presented with them.
• Some Ninja guys badges, as seen in S2E19 Bad to the Bone.
• Some dudes badges, in S2E19 Bad to the Bone. They run into both this guy and the Ninja guy on the way to the League. This random guy has insanely different badges from them.

I presume that Ash only goes to the suggested gyms because they're closest 8 to his home city. Gary can go further away to get different badges since he rides every where in a car.

Annnyways, that's all the random stuff I found. My belief is that pretty much every city in the region that wants a gym has a gym. Assuming that "regions" are bigger then they show them to be, even if each one was only the size of a small state like Rhode Island there would be room for dozens of gyms.