A trade is a process in which a Pokémon trainer sends one of his or her Pokémon to another trainer in exchange for one of the other trainer's Pokémon.

A trainer can trade with any person, him or herself or with trainers in the games. All a trainer needs to trade is two compatible game cartridges, two of the system it is on (Game Boys/Game Boy Colors for Generations I and II, Game Boy Advances for Generation III and DSes for Generation IV), a link cable for connecting the two systems (or a GBA Wireless Adaptor for trades between FireRed, LeafGreen and Pokémon Emerald) and at least one Pokémon. In Generation IV, Pokémon can also be traded via the Global Trade Station in Jubilife City.

Trading is important to getting all the Pokémon in the Pokédex, since there are some Pokémon that are not available in each version and some Pokémon that only evolve after being traded.

Trading also gives Pokémon an advantage in growth. A traded Pokémon gains boosted experience after a Pokémon battle, which allows a traded Pokémon to level up faster. Pokémon traded from outside of one's own country will gain even more experience.

Pokémon which evolve when traded

Poliwhirl → Politoed (if King's Rock is attached)
Kadabra → Alakazam
Machoke → Machamp
Graveler → Golem
Slowpoke → Slowking (if King's Rock is attached)
Haunter → Gengar
Onix → Steelix (if Metal Coat is attached)
Rhydon → Rhyperior (if Protector is attached)
Seadra → Kingdra (if Dragon Scale is attached)
Scyther → Scizor (if Metal Coat is attached)
Electabuzz → Electivire (if Electrizer is attached)
Magmar → Magmortar (if Magmarizer is attached)
Porygon → Porygon2 (if Up-Grade is attached)
Porygon2 → Porygon-Z (if Dubious Disc is attached)
Dusclops → Dusknoir (if Reaper Cloth is attached)
Clamperl → Huntail (if Deepseatooth is attached)
Clamperl → Gorebyss (if Deepseascale is attached)

List of in-game trades

This article is incomplete.
Please feel free to edit this article to add missing information and complete it.

Generation I

Jynx exchanged for a Poliwhirl at Cerulean City (Red and Blue only)
Nidoran♀ exchanged for a Nidoran♂ at Route 5 (Red only)
Nidoran♂ exchanged for a Nidoran♀ at Route 5 (Blue only)
Machoke exchanged for a Cubone at Route 5 (Yellow only)
Farfetch'd exchanged for a Spearow at Vermilion City (Red and Blue only)
Nidorina exchanged for a Nidorino at Route 11 (Red only)
Nidorino exchanged for a Nidorina at Route 11 (Blue only)
Lickitung exchanged for a Dugtrio at Route 11 (Yellow only)
Mr. Mime exchanged for a Abra at Route 2 (Red and Blue only)
Mr. Mime exchanged for a Clefairy at Route 2 (Yellow only)
Lickitung exchanged for a Slowbro at Cycling Road (Red and Blue only)
Parasect exchanged for a Tangela at Cycling Road (Yellow only)
Tangela exchanged for a Venonat at Cinnabar Island (Red and Blue only)
Electrode exchanged for a Raichu at Cinnabar Island (Red and Blue only)
Dewgong exchanged for a Growlithe at Cinnabar Island (Yellow only)
Rhydon exchanged for a Golduck at Cinnabar Island (Yellow only)
Seel exchanged for a Ponyta at Cinnabar Island (Red and Blue only)
Muk exchanged for a Kangaskhan at Cinnabar Island (Yellow only)

FireRed & LeafGreen

Nidoran♂ exchanged for a Nidoran♀ at Route 5 ([[Pokemon FireRed and LeafGreen|FireRed only)
Nidoran♀ exchanged for a Nidoran♂ at Route 5 ([[Pokemon FireRed and LeafGreen|LeafGreen only)