like you can you have to have dialga then you go to the house right behind the Pokemon center then talk to a guy and go in the bed when you fall asleep when you wake up you be on the iland where you can get darkri.
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
1. Catch it in a Pokémon GBA title with an event and migrate it to Diamond.
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.
Not in Diamond. Get it this way. 1. Catch it in a Pokémon GBA title with an event and migrate it to Diamond. or 2. Action Replay cheat code.
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.
Palkia, Lugia, Dialga, Deoxys, Mewtwo, and Mew
To answer your question, Birth Island doesn't exist in DPP.
You can't. The only ways you can get a DEOXYS in Diamond are you hack, use an action replay or game shark, or you migrate one from Hoenn and catch it in pal park. Good day to you.
You catch deoxys at birth island.
You can't catch Deoxys in Silver..
You can't catch Deoxys in soul silver