Well, if nobody uses Jynx then how is she remembered? Whevever somebody says that these Pokemon have all had their days, anybody can argue that every Pokemon was good at one point in time. Or another way is that every Pokemon has some place, whether it be a pre-evo to some slightly good Pokemon or has some small use somewhere, but to the rest of the world it is just useless. Then there is no Pokemon that is ever forgotten, and this thread is just spam. Back to Jynx, I know about the blackface thing, but that was so long ago that it doesn't really have a lasting effect on today.
Porygon-wise, nobody uses him in competetive TCG. Is far as I know, there are 2 Porygons that are legal for Tournament use Promo Porygon and Porygon2. Both are are useless. I know Porygon2 is a great wall in VG, but that doesn't affect Porygon himself, other than an annoying obstacle to get to a good Pokemon.
I don't know about Dewgong, but I know that nobody uses him in TCG. Within the past year only 1 Dewgong card was used, and it was a Fighting (namely Donphan) counter, which is now rotated.