I can.
1. Jigglypuff was one of the most commonly recurring pokemon in the anime from the indigo league to the Johto chapters, the most popular ones by far.
2. Jiggly is very popular in Japan, mostly with young girls. This is proven with many plushie and other Jigglypuff merchandise only available in Japan., and Jigglypuff has more of this advertisement than other pokemon due to its visual appeal to children.
3. Jiggly has also made prominent appearances in the manga. Green(The main character) owns one in Pokemon adventures, Red caught a Jigglypuff in Pokemon Pocket Monsters, and Ruby has one at home in the Ruby Sapphire manga. It also has made an appearances in Pokemon Magical Journey, Pokemon Zensho, and the electric tale of pikachu.
4. It's on a frickin plane
On the nose to be precise.
5. One of the most popular gen 1 pokemon(more so than eevee) as proven by its more important anime/manga appearances, merchandise, and appearances in 3 Smash games.
6. Jigglypuff is still given support as it was only pokemon from from gen 1 to receive a secondary Fairy typing so far.
7. Jigglypuff survived the cut over Mewtwo and Roy from Melee to Brawl.
and, to wrap things up, is original 12. It's not going anywhere.