Where to get fly in Pokemon Pokemon FireRed?

Answer 1

Once in Celadon City, go left towards the Snorlax blocking the road, then you will see a small tree you can cut down. Cut this tree, then continue going left and you will see a house with a little girl inside, she will give you HM Fly.

Answer 2

You get it from May when you battle her, i think you battle her on your way to Fortree City.

Answer 3

Fly is located in Route 16. Where Snorlax was, cut down the bush and to through the building. On the other side of the building is a small house. The lady inside will give you HM 2 (Fly).