The only way to get a Deoxys in Pokemon Heart Gold is to either trade it from another Pokemon game that has it, or use an action replay code.
There are only a few you can catch but the rest you have to get from trades with other games.
Deoxys is only available for capture in the 3rd gen games, so you have to transfer it over.
You catch deoxys at birth island.
You can't catch Deoxys in Silver..
Up ur pe nis
There might be but don't get your hopes up. No Information on this has been released in Japan or America.
You can't catch Deoxys in soul silver
You can't catch Arceus in Pokemon heart gold. You must bet it from Pearl, Daimond, or Platinum.
the metors switch its form by talking to it
When you catch Deoxys it is level 30.
By migrating Deoxys or an event.
No you can't catch deoxys by using cheats