I have received your message, ModelT. You got some good points in what you say, but still, it's a mistake having given Gengar and Gyarados such types. I mean, Gengar was the only Ghost Type in Gen I; and being part Poison type against a Psychic Pokemon, made him useless. No matter the description of the Pokedex, it should have been a pure Ghost Type from the beginning; so it could be useful against Psychic types. And as for Gyarados being Water/Dragon type too. After all, in Gen II, the only new Dragon type introducted was Kingdra (Water/Dragon). It's just they mess up with things in the games that don't have sense in the anime.