Pokémon evolutions by trading

This is a list of Pokémon that evolve by trading. The classic four evolutions (Alakazam, Machoke, Graveler and Gengar) from Red/Blue/Yellow evolve only by trading, while Pokémon from later generations require an item to be held in addition.

This information applies to any games that feature both Pokémon from the chain, so for example in Generation 1 the evolution chain with Steelix doesn't exist.

The Pokémon

Evolving from
Evolving to
Item
Poliwhirl Politoed King's Rock
Kadabra Alakazam
Machoke Machamp
Graveler Golem
Slowpoke Slowking King's Rock
Haunter Gengar
Onix Steelix Metal Coat
Rhydon Rhyperior Protector
Seadra Kingdra Dragon Scale
Scyther Scizor Metal Coat
Electabuzz Electivire Electrizer
Magmar Magmortar Magmarizer
Porygon Porygon2 Up-Grade
Porygon2 Porygon-Z Dubious Disc
Feebas Milotic Prism Scale
Dusclops Dusknoir Reaper Cloth
Clamperl Huntail Deepseatooth
Clamperl Gorebyss Deepseascale
Boldore Gigalith
Gurdurr Conkeldurr
Karrablast Escavalier Trade with Shelmet
Shelmet Accelgor Trade with Karrablast
Spritzee Aromatisse Trade holding Sachet
Swirlix Slurpuff Trade holding Whipped Dream
Phantump Trevenant
Pumpkaboo
Average Size
Gourgeist
Average Size