Kind of a long story, but the short version is: I thought I had an Alamos Darkrai to trade to someone on Fire Monkey Technology, but I realized I gave it to someone in order to let me borrow his Arceus, which was conveniently still on 4th Gen, which I needed it to be to trigger the Sinjoh Ruins event three times to get the Sinnoh Dragons. I did my thing, I gave him back the Arceus, and all was dandy. Mind you, this was back when news broke Nintendo Wi-Fi Connection was going down.
I don't have any private messages older than mid-April, so I don't know the guy's TSG name Also, I checked my Diamond Pal Pad, and I have no idea what I would've put for his name there. I do know two things: we arranged the deal over one of Alan's streams, and, as you can probably guess by the title, he gave me a Kricketot named Planket. If that Kricketot was yours, either post here or, when this inevitably gets locked, PM me letting me know, I'll probably know the name when I see it. I don't want the Darkrai back or anything, I just need peace of mind on the matter. Thanks, everyone!
And yes, I realize how self-indulgent this is.
EDIT: It was Ashigaru's Arceus I borrowed.