Gonna plug Pokémon Fool's Gold, a hack of Crystal where every Pokémon gets a regional-form-esque redesign. I've been quite enjoying it; it gives a fresh perspective on a lot of Pokémon.
It adds new areas, a few new trainers, new moves (both moves from later gens and wholly original moves), and the Physical/Special split. No Fairy type, though.
The dev team is also working on adding the Sevii Islands, along with Gen 3 Pokémon and the Gen 4 evos/prevos, and the Gen 8 evolutions (no longer regional). Oh, and Sylveon. Give it a look!