To answer your question, Birth Island doesn't exist in DPP.
No, you can't catch Deoxys on Pokemon Diamond & Pearl unless you have cheats. You can transfer it from your GBA to Pokemon Diamond and Pearl though
You catch deoxys at birth island.
No you can't catch deoxys by using cheats
Go to birth island.
Solve the puzzle and catch deoxys
You would need to use an Action Replay or transfer it from Pokemon Emerald, FireRed, or LeafGreen, for it is impossible to catch Deoxys in any location in Pokemon Diamond, Pearl, and Platinum.
You can catch Deoxys at Birth Island. However, unlike other legendaries in the game, you can't catch it under normal circumstances. You have to use an Action Replay/Gameshark to be able to access Birth Island and catch Deoxys.
Palkia, Lugia, Dialga, Deoxys, Mewtwo, and Mew
You can't. Deoxys Only comes as an event Pokemon in Pokemon Ruby, Sapphire, and Emerald. You would get a ferry ticket to Birth Island to catch it. There was also an event for Pokemon Diamond and Pearl for a Lvl. 50 Deoxys from Gamestop. Hope I helped out a bit!
You can't catch Deoxys in Silver..
you have to get more then 45 gym to catch legendary Pokemon! deoxys is a legendary Pokemon
Deoxys cannot be caught in the wild. You will need to migrate it from the Generation III games to the Pal Park or trade for it with a friend.