Below is a link for a google spreadsheet of 393 characters that are baked into Pony XL. you will find additional prompts for some that have alternate outfits. Characters are in alphabetical order and have their source paired with them and can be sorted by character name(default) or by source. The characters come from a mix of cartoons, anime, and video games.
https://docs.google.com/spreadsheets/d/1E18FJY6Qr2iC8ayf9iAyNCamWYatijINeHmqYzTyb_E/edit?usp=sharing