Who are the people who trade in Pokemon LeafGreen?

Answer 1

A trainer named Reyley trades you a Mr Mime for an Abra north of Viridian city,

West of Fuschia city in a big building upstairs a trainer named Marc will give you a Lickytung for a Golduck, In a house in Vermilion city a girl, Elyssa will give you a Farfethch'd for a Spearow.

In a house at Cerulean city a man named Dontae will give you a Jynx for a Poliwhirl, Somwhere in a underground path a little girl will give you a Nidoran female for a Nidoran male.

Then either its west of celadon city in a big building upstairs or east of Vermilion city or east of Fuschia city there is a guy who will give you a Nidorino for a Nidorina.