goto spearpiller
If you have Soulsilver, you need a Pokemon that knows the following moves: Flash Surf Whirlpool Sweet Scent Go to where you caught Lugia and then use sweet scent. If you're really lucky, Arceus will come.
no
get national pokedex and use flash on the first tile right after you go into spear pillar then glowing stairs will appear go up them
Arceus is not avabile. Right now, hack or use cheats to get Arceus.
Lets clear this up, shall we? Sapphire does NOT contain spearpillar. Diamond does.
Nope. It has to be a event Arceus.
You will see arceus in the same spot as Dialga and Palkia, only you will use the Azure Flute and stairs will appear. Then you will see arceus.
No, you do not need all of the plates to catch Arceus. You can use the plates to change Arceus' type, though. Arceus is only available by event (which has long since passed). You can also use an AR (action replay) to hack the game and get an Arceus, all without plates.
You could trade it from Platinum or you could use Wi-Fi to use the Nintendo Event: Arceus Special. If you are from Australia you can go to EB games and get Arceus for free in November
You can either use an action replay or you could have attended the arceus event in 2010.
If we are talking Game I don't know. Maybe Arceus since he can use a plate to use super effective moves against psychic type like mewtwo. If we are talking Anime Arceus. In the anime if Arceus has all life plates he is invulnerable.