Pikachu

Pikachu is the best known pokemon of all time, pokemon #025. It's been around since the origional Red, Blue, Green games. It's known as the "electric mouse" pokemon (personally I think he looks more like a bunny.) It is (as it's title implies) an electric type pokemon with no secondary type. It's only possible to have a pikachu as a starter in the Yellow game.

Bulbasaur

Bulbasaur is (according to the national pokedex) pokemon #001. It was introduced in the origional Red, Blue, Green games. It is the "seed" pokemon. From it's first stage it is a grass/poison type. It is an optional starter (the grass one, duh) in the origional Red, Blue, Green games, and the remakes of those games, FireRed and LeafGreen.

Charmander

Charmander is numbered 004 in the national pokedex. Like Pikachu and Bulbasaur, it is from the Kanto region of Red, Blue and Green. Charmander is the "lizard" pokemon. For it's first two stages it is just a fire type, then for it's third it's a fire/flying. It's the fire type starter in the Red, Blue, Green, FireRed, and LeafGreen games.

Squirtle

Squirtle is dubbed pokemon #007 in the national pokedex (and is my favorite pokemon). Like the first three, it is the final starter of Red, Green, Blue. Squirtle is the "tiny turtle" pokemon. It is the water type starter of Red, Blue, Gree, FireRed and LeafGreen, and it is the only Kanto starter (besides Pikachu who doesn't count) that keeps it's type constant.

Chikorita

Chikorita is pokemon #152 on the national pokedex's terms. Unlike the first four Chikorita was introduced in the Gold, Silver, Crystal games. Chikorita is classified as the "leaf" pokemon. Chikorita is only a grass type through all it's stages. You can choose Chikorita as your starter in the Gold, Silver, Crystal,HeartGold or SoulSilver games.

Cyndaquil

Cyndaquil has been Pokemon #155 since it was first introduced alongside Chikorita in Gold, Silver, and Crystal's Johto region. Cyndaquil is known as the "fire mouse" pokemon (again, don't ask me.) Like Chikorita, Squirtle and others, Cyndiquil gains no secondary type. In the Gold, Silver, Crystal, HeartGold and SoulSilver games Cyndaquil is a starter option.

Totodile

Totodile,Pokemon #158 made it's debut in the Johto region along with Cyndaquil and Chikorita in the Gold, Silver, Crystal games. Totodile is called the "big jaw" pokemon despite in obviously being an alligator. And like the other two Johto starters of Gold, Silver, Crystal, HeartGold, and SoulSilver games, Totodile has a single type through it's evolution.

Treeko

Treeko is Pokemon #252 (and my all-time LEAST favorite pokemon.) It origionated in the Ruby, Sapphire games (Emerald came out later.) Treeko is the "wood gecko" pokemon. It remains a grass type through all three of it's evolution stages. It is a choice as your starter pokemon in only the Ruby, Sapphire and Emerald games.

Torchic

Torchic is Pokemon #255 on the national pokedex's terms. It's from the Hoenn region of the Ruby and Sapphite games. Torchic has been determined as the "chick" pokemon, isn't that origional? Fron it's second stage it gains the secondary type of fighting, and all three stages are fire types. You can choose Torchic as a starter in Ruby, Sapphire and Emerald.

Mudkip

Mudkip has been classified as Pokemon #258. Mudkip completes Ruby and Sapphire's Hoenn starter trio. Mudkip is known as the "mud fish" pokemon, but I have no clue what it's based on. Like Torchic it gains a secondary type at it's second stage as a water/ground pokemon. It is an obtainable starter Pokemon in the Ruby, Sapphire, and Emerald games.

Turtwig

Turtwig is the first of the starter from the Diamond, Pearl, and Platinum games, Pokemon #387. Turtwig is classified as the "tiny leaf" pokemon, not just the "leaf" pokemon that's Chicorita. It starts as just a grass type, but it's final stage is also a ground type. You could choose Turtwig as your starter in your Diamond, Pearl, or Platinum game.

Chimchar

Chimchar has been dubbed Pokemon #390. It was created in the Sinnoh region of Diamond, Pearl, and Platinum. Chimchar is the "chimp" pokemon, as you can see, they are really running out of titles. It's evolution in like torchic's, gaining fighting as a secondery type on stage two. It's a starter option in the Diamond, Pearl and Platinum games.

Piplup

Piplup is known as Pokemon #393 and is from Diamond, Pearl, and Platinum's Sinnoh region. Piplup was given the title of "penguin" pokemon, as if gamers can't figure out that it's a penguin. It starts off a only a water type, but it's third stage is also a steel type. Piplup is the last optional starter in the Diamond, Pearl, Platimum games.

Snivy

Snivy is around 100 numbers above piplup as Pokemon #495. It's the first starter from the Black and White games. Snivy is labled as the "grass snake" pokemon.It is only a grass type throughout all three of it's evolutionary stages. Snivy is an chooseable starter pokemon in any (non-hacked) copy of the Black, White, Black2, or White2 games.

Tepig

Tepig is numbered as pokemon #498 ever since the national pokedex which was made before Tepig was. It's a Black and White Pokemon. Tepig is called the "fire pig" pokemon. It becomes a fire/fighting type at it's second stage, because we needed another one of those, thanks Nintendo. Tepig is a starter in Black, White, Black2, and White2.

Oshawott

Oshawott is way down the number line as pokemon #501. It's the third pokemon from Unova's Black and White games. Oshawott is also called the "sea otter" pokemon (if you thought it was gonna be water otter to continue Snivy and Tepig's theme you're wrong!) Oshawott can be your starter in either a Black, White, Black2, or White2 game.

More

Now, as much as I'd LOVE to go into detail about all 637 and counting pokemon. I'm just gonna give you a website for the rest so click here for all the rest.