PSA: the next time you have a chance to speak to a Game Freak employee who worked on Red and Green, be sure to remember to ask them about Pokemon that were among the 190 that were designed for, but scrapped from the final Generation 1 games.

Supposedly some of the scrapped designs made it into the later generations. Others, like #174 Dragon4 here are gone, for better or worse.

For reference (ignore the Johtomon in brackets, they mean absolutely nothing in terms of Gen 1 development period)
http://bulbapedia.bulbagarden.net/wiki/List_of_Pok%C3%A9mon_by_index_number_(Generation_I)