Rough WIP, likely needing both work and progress.
Malaconda, the Serpent Pokemon
Black: Its fruit was once used for medicinal purposes. This practice ended when patients reported terrifying visions.
White: Ancient homes were often abandoned after Malaconda nests were found inside. No one knows why these invasions stopped.
BW2: It grows fruit on its tail, which it uses to lure prey. When introduced to new regions, it starts growing different fruit.
Black and White both deal with old lore, and in keeping with the aesthetics of the games, White's lore is older. White's is also meant to make reference to Infiltrator. I originally tried to be more specific with Black's about how the fruit was used, but the simple mention of "medicinal purposes" is easier to manage in a short entry. BW2 is a more "standard" dex entry that brings us back to the present, and was sort of loosely inspired by the idea of different Arbok having different patterns.
Oh, and as usual, I posted this without reading most of the other entries. Hopefully I haven't "stolen" any ideas.