Go to the top of pokemon tower in lavender town and rescue Mr. Fuji (I'm pretty sure that is his name...) and afterwards he gives you a pokeflute. Use it to wake up the snorlax past celadon city.
You can find doduo either at the safari zone or you can find it at cycling road.
Cycling road is west from celadon city you need a bike to travel on the road but a snorlax blocks your way you need to use the pokeflute to make it wake up then catch it or defeat it now you can travel on cycling road.
if you mean rainbow badge go down cycling road and vs koga
You have to catch 40 Pokemon and get it from Professor Oake's aide. He can be found in the upstairs observation room in the gatehouse that connects Celadon City and Cycling Road.
Train at victory road
It is in victory road.
Above cycling road, you must use cut on that tree, then go through the building and you will see a house; go in and talk to the girl and she will give you fly.
You get it at wayyard cave below the cycling road.
it is in victory road when your going to the Pokemon league
The 'Cycling Road' is between Eterna and Oreburgh (it doesn't go directly to Oreburgh, but that is the nearest city).
Go to the very top of Cycling road. Go through the building there and there will be a spot where a Snorlax is (or was) then cut down the tree and go back through the building through the top section. When you get out, you will be on the very top of Cycling road, above the fence. There will be a house. Go in and the person there will give you Fly.
You can find TM Dragon Claw on Victory Road in Pokemon FireRed (Kanto).