There are 151 Pokémon in total, but no matter which version you have, there are Pokémon you simply won't be able to get unless you trade with friends. To complete the Pokédex you'll need to hunt down the rare ones, evolve them in various ways, and trade with your friends.
If you have friends who are starting new Pokémon games at the same time you are, agree beforehand who will get what in places where you're forced to chose between two or three Pokémon. Have one player get the Dome Fossil (Kabuto) and the other get the Helix Fossil, (Omanyte), one get Hitmonlee and the other get Hitmonchan, and decide who will evolve their Eevee into what. Then trade them all back and forth to fill out both players' Pokédexes.
When trading away your Pokémon, you keep the Pokédex entry for a Pokémon after you trade it away. So by trading a Pokémon to a friend you both get credit for having caught it, regardless of whether they trade it back or not. You do not get credit for the earlier evolutions of traded Pokémon. So if you receive a Venusaur, you'll still be missing Bulbasaur and Ivysaur. When trading Pokémon that are rare but also have evolutions, such as the starters and the fossils, trade them at every stage of their evolution.
Catching Pokémon[edit]
You'll get the vast majority of Pokémon by catching them in the wild. It is possible to get them all by trading between just the Red and Blue versions, but adding a Yellow player to the mix makes things easier. While there are no Pokémon exclusive to the Yellow version, Yellow players can easily get all three starters as well as rare Pokémon like Farfetch'd and Lickitung.
Legendary Pokémon[edit]
These Pokémon will only appear once, so if you defeat them you won't see them again. Save the game before battling them.
| Pokémon | Location |
|---|---|
 Articuno |
Seafoam Islands |
 Articuno |
Power Plant |
 Moltres |
Victory Road |
 Mewtwo |
Cerulean Cave |
Evolution[edit]
Some Pokémon require special steps to evolve their base forms.
Evolutionary Stones[edit]
There are 16 Pokémon that can be obtained when you use a Stone on their un-evolved forms. Only 2 of these, Raichu and Wigglytuff, may appear in the wild.
Trading[edit]
Four Pokémon can only be obtained when their previous forms are traded from another player. These final forms also never appear in the wild.
| Evolution | Requirements |
|---|---|
 Alakazam |
Trade Kadabra |
 Machamp |
Trade Machoke |
 Golem |
Trade Graveler |
 Gengar |
Trade Haunter |
Available from NPCs[edit]
Although not available in the wild, certain Pokémon are available by interacting with characters in the game.
You can only obtain these Pokémon by trading with specific NPCs:
| Obtain | Location |
|---|---|
 Farfetch'd |
Vermilion City |
 Lickitung |
Route 18 |
 Mr. Mime |
Route 2 |
 Jynx |
Cerulean City |
During the game, you will collect an Old Amber in Pewter City and either a Dome Fossil or a Helix Fossil in Mt. Moon. Taking these to the Pokémon Lab on Cinnabar Island will allow you to regenerate Aerodactyl, Kabuto and Omanyte respectively. As you can only collect Kabuto or Omanyte, you will need to trade with another player for the one you didn't obtain.
These Pokémon will be given to you as you progress through the game.
| Obtain | Location |
|---|---|
 Hitmonlee or Hitmonchan |
The Fighting Dojo |
 Eevee |
Celadon Mansion |
Mew[edit]
In addition to the 150 you can get by catching, evolving, and trading, there is a secret 151st Pokémon called Mew that was only officially available at Nintendo events but is also obtainable through the use of cheats and/or glitches. For more information on getting Mew see the Mew glitch page.