The only other 2 ways would be either to hack for it or to trade for it - there's no other way.
I am giving out Deoxys for only 3/21/2011.
add the DNS entry: 24.35.132.238 to your DS WiFi settings and log onto the GTS WITH YOUR PARTY FULL (It will go to the first open spot in your storage).
You must have a full party, or you may end up with a Pokemon with odd stats. To fix this, if you ignore this warning, give the Pokemon to the daycare and retrieve it..
you have to upload it through pal park from your leaf green or fire red. then catch it in pal park.
Deoxys doesn't come from a fossil, and can only be found through events from generation 3 games. If you want Deoxys in Diamond, you will have to migrate one through the pal park after you beat the Pokemon league.
Pal Park
Once you have opened the Pal Park in Pokemon Platinum, you can migrate Pokemon from Emerald (or any other GBA Pokemon game) to Platinum. The Pokemon you migrate can not be migrated back and they can only be captured in the DS game via the Pal Park
only throgh the pal; park
You can use the GTS :P
There is no deoxys in Pokemon platinum... u could only migrate to pal park from 3rd generation. :)
go to pal park
You need to migrate it from FireRed, LeafGreen, or Emerald. But if you have a Deoxys in Pokemon Ruby or Sapphire, then you can migrate from them to Pal Park.
no. If you have a Pokemon gameboy game migrate deoxys onto platinum and go to pal park on rt 221 and find it in the grassland area.
you have to upload it through pal park from your leaf green or fire red. then catch it in pal park.
You must transfer it from you GBA games and then capture it in the Pal park located in Platinum.
Once you beat the Pokemon league,turn off the game it will say migrate from emerald,sapphire,ruby,etc click on it have emerald,sapphire,ruby,etc in the GBA slot if you have deoxys migrate it go to pal park and catch it.
You can get Deoxys in Pokemon FireRed, LeafGreen, and Emerald by using a GameShark, for the Nintendo event has expired. In Pokemon Diamond, Pearl, and Platinum, you will need to transfer Deoxys from any of the GBA games to the Pal Park, or simply trade with a friend who has it.
I don't think there is a code. But i know a few methods to get the Pokemon. 1.you can trade it from Pokemon Platinum,Pokemon Diamond,or Pokemon Pearl. 2.In Pokemon,Platinum,Diamond and Pearl there is a Pal Park,(You need national dex),which you can get your old Pokemon from LeafGreen,FireRed,Ruby,or other Role-Playing Pokemon games. 3.there is a code,a Pokemon modifier,were you can get Pokemon 1-493. I hope i helped if you look on Google for "heartgold deoxys ar codes" it should be the 5th link
Deoxys is not a Pokemon you will be able to capture in this game. As far as I know you could only get it in the GBA games through mystery gift. If you did happen to get that mystery gift, then you can transfer it through pal park.
you can using cheats,trade or using pal park but without 1 of those 3 u cant