Pokemon Cyan is a FireRed hack of chrunch in PokeCommunity. Your main storyline will happen based on what you have decided. Many Pokemon are mixed with Fakemon at the same time in a brand new updated region.
Pokemon Cursed: Well, another hack made from a floating creepypasta on the Internet, made by Reidd.
Pokemon Crush is a hack made from Pokemon Ruby and it is in Spanish, not English. The author, RedMort, is a Spanish himself (maybe this is the most reasonable excuse for the language of this game).
Pokemon Creepy Black is a very strange Pokemon hack made from Pokemon Fire Red. This is not an ordinary hack. Instead, it has a creepypasta along.
Pokemon: Chronicles of Soala is a hack version made from Pokemon FireRed. Its author is a moderator on PokeCommunity some years ago. At the first place, he didn’t intend to do it because it was an April Fool joke.