So, because I know how boring it was, here are the edited file.
https://drive.google.com/open?id=1Woccg ... T5FyYkvibo
To use it:
-go to config in your .minecraft folder. You'll see a "pixelmon" file that you can edit with a code editor.
- at the 1/3 of the page, you'll find a line "useExternalJSONFilesSpawning=false". Replace the false by "true". if yoy want to edit anything else, go back to this file.
-a folder named "pixelmon" will appear. if it doesn't, open and close minecraft and go check if anything changed.
-in this new folder, go to spawning-->default, and replace every Pokemon file by the new one. I change the rarity by each one of them by "0" because my life is potato. You'll also need to place those files in the standard child-file.
The operation doesn't affect spawners and special spawn (mega-boss, shinys, rocks,...)
One error I've commited before was that, in the config file, I fought that desactivate the generation spawning (generation 1, 2, 3,...), it would work. it did, but I couldn't choose a starter.
I hope I've helped you. Bye!