I certainly remember Jumpluff; the line is one of my favourite grass types, actually.
It used to be Huntail/Gorebyss, but now I do remember them due to the fact that they were so forgettable. Same deal with Qwilfish, Stantler, and Masquerain. Burmy and its evoutions also no longer qualify for me, due to that 15 Worst Pokemon video.
Right now, it would be... hmmm, that's tough. Since I wouldn't remember the Pokemon, and thus be unable to say what it is... er, perhaps Lileep/Cradily? Even though it's a fossil Pokemon, I tend to forget about it a lot compared to every other Fossil Pokemon.
When Snake sees a "!" over someone's head, he runs and hides. When the Pokemon Trainer sees a "!", he beats them up and takes their money.
Stantler is one of those Pokemon that's so forgettable, everyone remembers it because of its sheer blandness. It's like, "Wow, I've never seen something this bland. Seeing something this forgettable is a once-in-a-lifetime experience. I shall treasure this memory forever."
It's the same case with Tauros; so unforgettably forgettable.
"I desire to go to Hell and not to Heaven. In the former I shall enjoy the company of popes, kings and princes..." - Niccolo Machiavelli