Using Action Replay
The Action Replay is a code device that plugs directly into the cartridge slot of your Game Boy Advance. At the top of the Action Replay is a cartridge slot where you insert your desired game cartridge. To start using your Action Replay, simply plug "Pokemon Ruby" into the cartridge slot of the device, then insert the Action Replay into your Game Boy Advance. Once you turn the system on, the code screen will pop up, allowing you to input whatever codes you want.
Aurora Ticket Code
With this code, you will receive many key items in your bag. Among them is the Aurora Ticket. At the code screen, enter "E313fc0a Db6219cf 4637223e A59fd2e6 Ad7ddea1 8d70839c 5bf3c017 Bf4eecbe D29512de 557c782a Fbf15e16 Fba84931 399fd57b 5c105172 337f00fe 58c4a878 96f33985 43d97a7f Bad43420 Ef3adbb9" and press "Start." Load your save file and go to the sailor at the southern part of Vermillion City. Show him the ticket and he will take you to Birth Island where you can battle Deoxys.
Walk Through Walls
At the code screen, enter the code "Cf010edc Cb42Fc3a 78da95df 44018cb4." Press "Start" to begin the game and load your save filed. This code allows you to walk through walls, people, trees and any other obstacle in the game. Travel all the way to the southern part of the map to reach Birth Island. Once at Birth Island, you can battle and capture Deoxys.
Warnings
Using any Action Replay code with your game can corrupt your save file or, worse, corrupt the game itself, as the Action Replay devices messes with the game's programming. In addition, by using an Action Replay on your copy of "Pokemon Ruby," you will be unable to use the game in any official Nintendo-sponsored Pokemon tournament.