Instructions
Trading for Game-Specific Forms
Acquire Deoxys, either from a legitimate trade, Nintendo event or hacking your game.
Prepare the receiving game to trade with Ruby. Some later generations require users to complete the game to unlock transfer capabilities to previous games. It may even be necessary to systematically trade up, as Pokemon Black and White, the latest entries as of publication, are incompatible with GBA Pokemon titles.
Trade Deoxys to the other game. Depending on the game traded to, Deoxys will assume one of four forms. A list of compatible games and their corresponding forms is included in "Tips."
Trade the changed Deoxys back to Pokemon Ruby.
Changing Forms at Will
Acquire Deoxys, either from a legitimate trade, Nintendo event or hacking your game.
Prepare the receiving game to trade with Ruby. Some later generations require users to complete the game to unlock transfer capabilities to previous games. It may even be necessary to systematically trade up, as Pokemon Black and White, the latest entries as of publication, are incompatible with GBA Pokemon titles.
Trade Deoxys to a fourth generation (Diamond, Pearl, Platinum, HeartGold, SoulSilver) or fifth generation (Black, White) Pokemon game.
Take your Deoxys to the appropriate location for changing its form. This location varies from game to game. In Diamond, Pearl and Platinum, you must take it to Veilstone City. In HeartGold and SoulSilver, you must take it to Kanto Route 3. For Black and White, you must take it to Nacrene City.
Find the meteorites in the area. In Veilstone City, they are located in the Southeastern corner of the map. On Kanto Route 3, they're located along the Southwestern edge of the map. In Nacrene City, they are located inside the Nacrene Museum, as part of a meteorite exhibit. Each meteorite will confer a different form to Deoxys upon examination, and the form can be changed as many times as desired. When you've selected a form, trade Deoxys back to Ruby version.