It depends on what you prefer. Everything has a weakness. My personal favorite - Charizard - is pretty much dead when put against electric or water types. However, it is generally accepted that Mewtwo is the ultimate pokemon from the originals. However, because it is psychic, bug and ghost type moves will still super effect it. Dragonite is nearly unstoppable, unless you have ice power, or another dragon type.
All of the starter Pokemon are the best
pokemon blue
Venusaur, since its a starter. Or Victorybell.
mewtwo
Electrive Electrive
Has to be Blue, In my opinion.
cinabar island
A blue gummi is a food item in Pokemon Mystery Dungeon that increases your IQ. It works best for Water-type Pokemon.
Voltorb is the best choice cause he isn't useful
Easily Pokemoncheatscodeswalkthroughs. There are few really good Pokemon sites out there for Red and Blue (Kanto), and this is by far the best. Note that this site is constantly updated: www.pokemoncheatscodeswalkthroughs.webs.com
There is no best Pokemon. All Pokemon have type advantages. My best advise is to get a flying Pokemon, an electric, a grass, water, fire, and a rock/ground Pokemon (Geodude is good)
Pokemon Red & Blue with 23.9 Million copies sold as of 2009.