Pokemon Arcoiris is a Pokemon ROM Hack of Pokemon Ruby which is made by Numus and Ra. Language. The game is in Spanish.
Pokemon Chaos Black is definitely one of the most excellent Pokemon Hacks. It is a hack version of Pokemon Fire Red in English.
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.