Only if you got the event.
to get shamian, darkria, and arseas can only be done in a time event here is a great secret that Nintendo does not want you to know about with mistery gift go on wi-fi conention on the Nintendo event day you will either get arseas, darkria,or shamian
If you're talking about Arceus, the only way you can get that is through a trade from a Diamond/Pearl/Platinum game, or as a special event item.
How do you get arseas with the national pokedex its me Brian and I have got the national pokedex. without mystery gift. I and r near a pokemart.action replay.cheats and anything else like numbers pleas say yes. Name:Brian Natianal pokedex:yes dude Brian has got the naiotnal pokedex Street:acorn way number 12 white door. or you could give me your platnam version and I could keep It for ever. give me arseas please or say yes.
You have to do multiplayer with a friend who has a DS and either platinum, pearl, or diamond, and sneak into their secret base and steal their flag and bring it to your base. (beware of traps that they have set)
First you need to get the Azure Flute. The 'Action Replay code for the azure flute is this: 94000130 FCFF0000 B2101140 00000000 0000B5D4 0000000A D2000000 00000000 Then you got to the Spear Pillar you will be told to play it. After that all these steps appear and you will go up them until you reach Arceus. BE WARNED He is at level 80 and is very strong. I would recommend a Master Ball. The 'Action Replay' code for that is: 94000130 FCFF0000 B2101D40 00000000 E0000D00 0000003C 03E70001 00000000 D2000000 00000000 Then you throw it and you've got him.