The Flute doesn't exist in the Crystal version. However, you can find a program for your radio when you update it when the generator is fixed. After it is fixed, go to the radio tower located in Lavender (Not the Goldenrod one) and speak to a man inside. He will upgrade your Pokégear to let you listen to the programs in Kanto. One of them is the Pokéflute program.
You can find the Poke Flute in the Pokemon Tower. After you free Mr. Fuji, he will give you the Poke Flute.
In poke marts
There is no Poke Flute item in Pokemon Silver. Instead, the player can have their radio upgraded in Lavender Town. It will then play a station that can play the Poke Flute tune.
Heres a big cheat to get the poke flute go to celadon city and buy a poke doll located on floor 4 then go to Pokemon tower then find the ghost that block's the stairs then use the poke doll to flee and go upstairs and beat the rockets then get the poke flute.
You can't.
You can find the Poke Flute in the Pokemon Tower. After you free Mr. Fuji, he will give you the Poke Flute.
use the app on the pokegear and go to the music thing and go to #20
move the dot to the top, you should find the poke flute channel
save mr.fuji from Pokemon tower top floor and get the poke flute
In Pokemon Crystal, to obtain the Poké Flute (which is what I assume you meant by "poke lullaby"), you need to first wake up Snorlax blocking the path on Route 11. You can do this by getting the Expansion Card from the radio station in Lavender Town and tuning your radio to the Poke Flute channel. Once Snorlax is awake, you can capture or defeat it to clear the path.
In poke marts
There is no Poke Flute item in Pokemon Silver. Instead, the player can have their radio upgraded in Lavender Town. It will then play a station that can play the Poke Flute tune.
ask the little children they know you want them
you cant use a poke flute on party pokemon
Heres a big cheat to get the poke flute go to celadon city and buy a poke doll located on floor 4 then go to Pokemon tower then find the ghost that block's the stairs then use the poke doll to flee and go upstairs and beat the rockets then get the poke flute.
you beat the haunted tower next to the psycic gym
you fist have to go throuh the not hard maze in the pokemon(ghost) tower and find the old man. go back to his house (the day-care) and you got it