Go to the event but its tough to beat
You don't need to cheat that much, just a little to get the Azure Flute and from their you can summon Arceus and catch it normally
In platinum the first event of 2010
In November there is special event to get arceus
You have to go to a nintendo event to get the mystery gift.
No. I put "Everyone Happy" and "Wi-Fi Connection" and I got the mystery key for Rotom.
Not possible unless you get the azure flute from a nintendo event but it rarely happens.
First you need the Azure Flute ( the Azure Flute is an event item,so use cheat special event to get it ).After getting special event cheat,go to the nearest Poke Store(except for Veilstone City Mall).You will see a green man.Talk to him and he will give the Azure Flute right away.Now go to Mt. Coronet.Go to the Spear Pillar at the peak of Mt. Coronet ( Where you battled Dialga and Palkia ). When you are in Spear Pillar,a message will be sent to you.It says that the Azure Flute plays with the wind and you will be asked to play it.Say yes and a sparkling,tall stair will appear. It will lead you to the Hall of Origin.There is ARCEUS waiting,be sure to catch it ( you can use this again and again when you have special event ARCEUS.
You have to get the mystery gift then talk to the green sutid guy he gives the azurl fluite then to the top of mount cornet then play the fluite but be careful its very very tough its level 90