>>37867649Fluttershy, RD, Twilight and Starlight are entry level, later there's better versions of them like Marble, Coco, Spitfire, Moondancer, etc.
When you advance a bit there's
the CMCs Celestia and Luna, Pinkie, Applejack, and Rarity, there's no direct upgrades for them, but they're shown proeminently
Then when you advance you get into the more famous secondary cast, Octavia, Lyra, Trixie, the already mentioned Marble, Spitfire, Coco, Moondancer, Maud, RD's mom, etc. they're more famous in the fandom than shown in the show itself
After that you go for the less famous secondary cast, Limestone, Vynil, Photo Finish, Saffron Masala, Sonnambula, Bonbon, etc. ponies that were never quite famous or were famous once but then died down a bit
After that you'll go to the background ponies, like the ones usually associated with the whole Mareschizo thing
After that, you're going into OC and headcanon territory, things like Barb, Nightmare Rarity, Milky Way, Mean Twilight, Little Pip, Gleaming Shield, etc. This is the acceptable limit of obscurity and autism
Once you cross that line, you'll go for demented things, Spike, background fillies, Rumble, Cozy Glow, Whoa Nelly, but there's more
After that you'll have a character + some fetish that you attached to them, one could count that as a regular character but the mind is so twisted that you can't separate the pony from the fetish, things like morbidly obese Twilight, zoophile Fluttershy, trans Trixie, etc. if you find yourself here, go find Jesus, Celestia, or the nearest shotgun