You can't without migrating from fire red/leaf green
How Do You Get Moltres,zapdos, And Articuno In Pokemon Diamond?
You go to pal park and porfisser oke will be they he will bla bla bla and he will walk out go to etina and go to his house and he will bla bla bla and then go to the marking map and the icons will aper
To get moltres,zapdos and articuno you have 2 go to pal park and look for professor oak he is hidden and if you talk to him look on the pokemon watch for the screen that helped you catch mesprit and three more icons will apper and they will be moltres,zapdos and articuno
I don't think you can get it in pokemon diamond & pearl
Go to the mining museum and talk to the guy behind the counter. (make sure you have no fossils with him already) my friend tried and it was a success! Please note that she talked to him for the first time...I tried later but I had talked to him previously so it didn't work.
Happy day to who ever reads this!
Happy day to who ever reads this!
Go to Eterna city and talk to Dr. Oak - he will talk about then being cited in Sinnoh, then use the marking map to find all three legendary birds. - not sure if it works in Diamond, but it does in Platinum I know that but you should try it