You do it
to the left of eterna city,
Take it to oak in Eterna city after you beat the elite 4
In the Eterna gym in eterna city.
the galactic hideout but i think you need to beat the gym leader before you can get through.
After you beat the game he is in eterna city in the house right at the end of the town by route 206
Moltres will roam around the region in Pokémon Platinum after you talk to Professor Oak in Eterna City once you beat the Champion.
In eterna city for platinum
west of eterna city
Eterna City
it's between Eterna Forest and Eterna City
in eterna city
hearthome city