Okay, this thread is pretty much dying, and I did get a couple of good comments for my submission(s). It has really worried me throughout the thread that I got nothing out of Wyverii, Doug and Rising_Dusk, but I'm going to try and at least get slated because I respect the opinions of these people.
Final Submission
Species: Soul Trap Pokémon
Black: When it meditates, it is actually hunting for souls. Its shadow can extend up to 300 feet to ambush its victims.
White: Its human-shaped flower stores the souls of its victims. This allows it to contact the spirit world.
The thing that has dawned on me lately is that a human-shaped Pokémon is a pretty bad lure for Pokémon or their spirits. Wild Pokémon tend to be afraid of humans, after all. On the other hand, I wanted to avoid going in a direction like Deck Knight's, where it would "lure men" or some such. Hence, as much as this Pokémon tries to be a flytrap, it's just not realistic for it to behave like one literally. If it wants to hunt, it must do it a bit more actively. You could say this is a flytrap, but not a flytrap... a soul trap, maybe?
You can consider this a "down-to-earth" entry that treats Necturna as a plant using ghostly elements, rather than a spirit using plant elements in a vague way. Black is a bit longer than I would like, but putting a number to its "attack range" is appealing to me because it's the kind of thing a Pokédex entry might do. White is largely an inversion of Rising_Dusk's suggestion as well. Looking back, I think that this whole "mean CAP vs nice CAP" thing is not the way to go at all, and so I've just gone with the "this is a plant and it does cool things" route. I know some people might complain that my attempts are getting more "depressing" as time passes, but I wouldn't say that it's even all that morbid (zomg something eats something else!!??) and is certainly less so than most of the "mean CAP" submissions and even some of the "nice CAP" submissions.
This also plays into an easy extension of the lore if we ever decide to make pre-evos. I just had an off-hand idea that these Pokémon are used by spirit media (maybe they even plant them themselves) to help in contacting spirits or for ghostbusting :P However, I can only fit so much into a humble dex entry.