If you're willing to look at a local Wal-Mart or other similar chain, you could spend around 15 bucks on an Action Replay. I highly recommend the software myself, as I am a hardcore gamer. I used it alot. Until it froze... but its simply overlooked as it's easy to fix with the right cable and PC software. GO GAMING!
To get Arceus on Pokmon, you need to download it using a software that is in its new version. You can also contact Nintendo through email to help you get it. Read more at http://en.wikipedia.org/wiki/Arceus.