Due to a request, I have started a simple guide showing which NPCs will trade Pokemon with you. If you know any information of any NPC I missed or of the trade itself, please comment below and I will add it in.

 

General Information:

- Iv's, nature and ability of the Pokemon you receive is random.

- Pokemon you receive may be shiny. (probably same 1/81xx rate).

- Trades are one-time only.

 

Kanto:

Location: Viridian City (southeast)

NPC: Madeline

Pokemon: Wants to see a Pidgey with over 15 ivs in Attack and Speed for an Oddish (not holding anything)

 

Location: House North of Viridian Forest

NPC: (unnamed)

Pokemon: Give them a Nidoran(F) for a Nidoran(M) (holding a Moon Stone)

 

Location: Route 2 Stop 3 (where Oak's Aide is for Flash HM)

NPC: (unnamed)

Pokemon: Give them an Abra for a Mr. Mime (unknown if holding anything)

 

Location: Mt. Moon PokeCenter

NPC: Magikarp Salesman

Pokemon: Give them $1,500 for a Magikarp (not holding anything)

 

Location: Cerulean House 3 (west of PokeCenter)

NPC: (unnamed)

Pokemon: Give them a Poliwhirl for a Jynx (not holding anything)

 

Location: Cerulean House 5 2f (east of PokeMart)

NPC: (unnamed)

Pokemon: Give them a Clefairy for a Cleffa (unknown if holding anything)

 

Location: Vermillion House 1 (west of PokeCenter)

NPC: (unnamed)

Pokemon: Give them a Spearow for a Farfetch'd (holding a Stick)

 

Location: Celadon Mart 5

NPC: (unnamed)

Pokemon: Give them a Magmar for a Magby (not holding anything)

 

Location: Bike Road Stop 1F (House inbetween Cycling Road and Fuchsia City)

NPC: (unnamed)

Pokemon: Give them a Golduck for a Lickitung (not holding anything)

 

Location: Fuchsia PokeMart

NPC: (unnamed)

Pokemon: Give them a Mr. Mime for a Mime Jr. (not holding anything)

 

Location: Pokemon Lab 2 (Closest Room in Pokemon Lab on Cinnibar Island)

NPC: (unnamed)

Pokemon: Give them a Raichu for an Electrode (unknown if holding anything)

 

Location: Pokemon Lab 2 (Closest Room in Pokemon Lab on Cinnibar Island)

NPC: (unnamed)

Pokemon: Give them a Venonat for a Tangela (not holding anything)

 

Location: Pokemon Lab 4 (Furthest Room in Pokemon Lab on Cinnibar Island)

NPC: (unnamed)

Pokemon: Give them a Ponyta for a Seel (unknown if holding anything)

 

Johto:

Location: Violet City (East of the School)

NPC: (unnamed)

Pokemon: Give them a Bellsprout for an Onix (unknown if holding anything)

 

(Unconfirmed)

Location: Route 31

NPC: ???

Pokemon: Give them a Dugtrio for a Magneton (unknown if holding anything)

 

Location: Goldenrod City (Directly south of the PokeCenter)

NPC: (unnamed)

Pokemon: Give them a Drowzee for a Machop (holding Macho Brace)

 

Location: Eructeak City (Above Dance Theatre/PokeCenter)

NPC: (unnamed)

Pokemon: Give them a Haunter for a Xatu (not holding anything)

 

[unconfirmed]

Location: Olivine City

NPC: (unnamed)

Pokemon: Give them a ??? for a Voltorb (holding a Metal Coat)

 

Location: Blackthorn City (Northwest of the PokeCenter)

NPC: (unnamed)

Pokemon: Give them a Dragonair for a Shelgon (holding a Dragon Fang)

 

Sevii Islands:

Location: Altering Cave (Northeast Corner)

NPC: (unnamed)

Pokemon: Give them a Dragonite for a Goodra (not holding anything)

 

Hoenn:

Location: Petalburg City House 2 (West of PokeCenter)

NPC: (unnamed)

Pokemon: Give them a Ralts for a Slakoth (not holding anything)

 

Location: Valley of Steel Weatern Peak (West of PokeCenter)

NPC: Laila

Pokemon: Give them a Buizel for a Ferroseed (not holding anything)

 

Location: Valley of Steel Eastern Peak (South of PokeCenter)

NPC: Cronky

Pokemon: Give them a Bisharp for a Klefki (not holding anything)

Great idea for a guide!

 

Btw, the Farfetch'd from that girl is holding Stick

The guy from Pokemon Lab 2, he's trading electrode for raichu. im not that 100% tho

Updated. Thank you for your contribution.

Johto blackthorn dragonair for npc shellgon holding dragon fang

For the Pokemon Lab 2 NPC. I think it's a Venonat for Tangela

 

Also, in Johto:

Violet City:

Bellsprout for Onix

 

Goldenrod:

Biker near pokecenter.

Drowzee for his Machop (holding Macho Brace)

 

Ecruteak City:

NPC above pokecenter(???) Haunter for his Xatu

Updated, thanks!

thanks for information :y:

they added npcs that trade:

 

a magmar for a magby (5th floor of Celadon department store)

 

a mr. mime for a mime jr. (Fuchsia Pokemart)

there is a clefairy for a cleffa in one of the houses in cerulean city too