Pokemon Chaos Black is definitely one of the most excellent Pokemon Hacks. It is a hack version of Pokemon Fire Red in English.
Pokemon Ash Gray is another Pokemon Hack that uses the events of Pokemon Animes to make a new gameplay for Pokemon Fire Red.
Pokemon: Ash’s Quest is really a complete remake of Pokemon Fire Red. Now you can see almost 82 episodes of the Pokemon Anime into this hack.
Pokemon Adamantite is an amazing Pokemon Hack because the creator of it rauzeruk wants to show the best of Pokemon Diamond/Pearl/Platinum into Pokemon Ruby.
Pokemon Ambar is an interesting remake of Pokemon Ruby (US). The author Goce wants to bring the new magic lookings and his mother language into Pokemon Ruby.
Pokemon Flora Sky is an excellent ROM Hack of Pokemon Emerald with a lot of new features including 2 versions: Main Version and Complement Dex Version.