In every mainline Pokémon game, there are certain Pokémon that have specific requirements to evolve, with some evolutions only accessible via trading. Additionally, out of the ten trade evolution Pokémon in FireRed and LeafGreen, six require the Pokémon to be holding a specific item before the trade.

A list of all trade evolution Pokémon in FireRed and LeafGreen can be found below, along with any additional requirements:

Trade Evolution Pokémon

Evolving from…		Evolving to…	Condition
#061 – Poliwhirl		#186 – Politoed	Trade holding King’s Rock
#064 – Kadabra		#065 – Alakazam	Trade
#067 – Machoke		#068 – Machamp	Trade
#075 – Graveler		#076 – Golem	Trade
#079 – Slowpoke		#199 – Slowking	Trade holding King’s Rock
#093 – Haunter		#094 – Gengar	Trade
#095 – Onix		#208 – Steelix	Trade holding Metal Coat
#117 – Seadra		#230 – Kingdra	Trade holding Dragon Scale
#123 – Scyther		#212 – Scizor	Trade holding Metal Coat
#137 – Porygon		#233 – Porygon2	Trade holding Upgrade