Well, I got mine. As we all know, Level 100, so no EVs beyond Vitamins (a fellow DS-user was complaining about that when I went to download). Also, its Nature is Bold (-Attack, +Defense), so if you're not going for some in-battle boosts you'll want to be focusing on the Special side.
I see the whole Level 100 shpiel as encouraging Arceus's as a jack-of-all-trades Pokemon and preventing the raw overpowering storm that would be Smogon-esque manipulated stats. It's a known fact that with the inability to breed, legendaries are a bit tougher to nail on specific IVs and Natures (I cannot help but laugh at the absurdity of using Hidden Power on Raikou in-game, and there is not a single Smogon moveset that works without it). Arceus simply takes that to a greater extreme in exchange for its unmatched Base stats.
Look at this way. Without a Nature boost, any of Mew's stats (besides HP) with maxed EVs will range from 268 to 299, which can be done in only two stats. Arceus, even with only 100 EVs (Vitamins) can range from 270 to 301, and that can be done five times over. I don't think that's too shabby.
Bigger issue would be the pressure of it's promotional-only moves. Using them all you don't have a very great Pokemon. Delete them and they're gone forever.
And you know, on an unrelated note, I'm really hating the whole berry-growing shpiel. I decided I'd need about nine Qualot Berries (lowers Defense EVs). So, I got to planing. Now I have to wait EIGHT HOURS PER STAGE, totaling over a full day, before I can use them.
And people wonder why I hate the EV cap.
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