No you can't catch deoxys by using cheats
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 can't.
You cant on these games....try Ruby, Emerald, Saphhire, Leaf Green or Fire Red (and only then with cheats!)
The only way to catch Deoxys is by going to a Nintendo Event (which already passed), or get Deoxys from a friend who is willing to trade one via Wi-Fi or via Wireless connection.
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 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.
its impossible without cheats
Palkia, Lugia, Dialga, Deoxys, Mewtwo, and Mew
To answer your question, Birth Island doesn't exist in DPP.
in a fossil
You catch deoxys at birth island.
You can't catch Deoxys in Silver..