Moved and merged your thread on discussing Pokémon #666 here.
It has come to mind whether or not GameFreak would create a Pokémon to sort of recognize the omen that is the number 666. If I recall, however, Japan doesn't necessarily see the number six as an unlucky number - at least not in the same vein as the number four and nine. The most they might do is make it a Ghost or Dark Pokémon or just look over it completely. After all, Pokémon #444 is a Gabite and there's nothing unlucky about it. Actually, in Diamond, its PokéDex entry says its scales are said to be able to cure practically any illness.