>>57115174That would be Gold/Silver 97' Reforged, a hack that's based around the Spaceworld leaks from a few years ago, including old trainer concept sprites, the prototype Johto region called Nihon (with its own post-game archipelago), and the lost betamons. It feels very distinct and I'd recommend it, you can even toggle the SW97' type chart if you want.
Didn't include any betamon designs in this, but you can check out the Pokedex with all of them here:
https://docs.google.com/spreadsheets/d/1YSW6vEl4YAMdRoV8x5GuRZm7OShrmlnugF_8eeto504/edit?usp=drivesdk 