Hey! I recently discovered your system after finding it in a lot of collections shared by my own fan game (a Final Fantasy TRPG system). I really dig the mechanics you devised, it's the Pokémon TRPG I've always dreamed of. I've seen many other popular projects like PTU, but I've always been turned away for the unnecessary amount of bloat. I think using Pokémon Showdown is a brilliant solution to account for the insane amount of variables that must be considered with Pokémon combat. I'm currently planning a big campaign for some friends, and I wanted to see how far I could stretch your mechanics. As a result, I ended up home-brewing a lot of extra rules to account for various features from the video games and added guidelines to make the process of using Showdown easier.
Because of the sheer volume of extra content I added, I ended up formatting it into a proper rules expansion. I thought I'd share it here so that others can use it as well!