I forgot to add something: doing the Event at Sinjoh Ruins gets you the Orb attached to the Pokémon chosen. Of course, you can't import the Orb into Gen. V, having to use the one obtained at Marvelous Bridge (B/W) or somewhere else (B2/W2).
Believe it or not, yes. If you have the Toys 'R Us Arceus, you can trigger a special Event at the Ruins of Alph if you have it as your walking Pokémon. That Event leads you to the Sinjoh Ruins, a small area that is fully enclosed and where you get to run into Cynthia of all people. You can't leave until the Event is over (a good thing since you can only do it once).
There is only one thing that is illegit. about my trio: they're all in my OT. I used an Action Replay to repeat the Event and get one of each; normally, you CAN get a second, using a different Arceus later and under a different circumstance that triggers it again, but the third is impossible under normal circumstances (probably to get people to trade, again).
The actual acquisition is itself legal (went through the whole thing each time) and this is a valid Pokémon; I did not repeat the Event for the same Pokémon, either, for IV purposes (besides, that's five minutes every time, I'd get bored fast, and it can't be used in many online things either except the DW).