go to a event
there isn't pokeflute in Pokemon pearl or diamond
pokeflute
not without cheating
By cheating
I'm pretty sure you can't find any flutes in Pokemon Pearl.
cheating
to get Manaphy without cheating, you have to have Pokemon Ranger, beat a certain mission, and then somehow transfer the Manaphy egg to Diamond or Pearl.
Pokeflute is on the Pokemon radio when you are in Johto or Kanto.
Not without cheating, you can't.
You can't without cheating
You can't without cheating.
Only by cheating or hacking.