Yes she will return... I think!

I don't care. For me Jigglypuff in Smash is a worse Kirby. It was popular when it always sang its song in the Anime. But these days are over. So we don't need it anymore. It was in all the Smash games until now. So if it is in the new Smash it will be just because of nostalgia.

Yes and they need to bring back Mewtwo along with it's mega evolution's for its final smash.

Seeing as how the pokemon trainer is most likely no longer returning because of no transformations and Charizard being by himself it opens up 2 more slots to replace squrtile and ivysaur. I think Jigglypufff will defiantly be returning but wont be announced until release or close to it because its always been one of those hidden characters.

Both have been there sense the very begining there chances of returning are very, very high. I wouldnt worry much.

He is tradition, but even so 5 pokemons are streching it. That's the absolute max IMO.

5 slots would match the mainline Mario characters, so it's not too many.

She's pure grandfather clause at this point.

Actually, the reasons are very obvious to those who have some understanding of the situation.

Jigglypuff is very popular in Japan. This was why Jigglypuff made it into the original Smash Bros. Jigglypuff is also quite easy to animate, and the moveset is rather unique yet simple. Given all of this, including Jigglypuff in the new games is a no-brainer; it would take relatively little effort to develop the character model, moveset, etc, and thus Jiggles wouldn't take up a slot that could have gone to another character.

As someone who was 10 when the anime came out, and grew up with the Jigglypuff hype (HE SINGS! THEN DRAWS ON THEIR FACES!) I think it's her time to rest. Has it even been in the show in the last 10 years? Do any of the generation after gen-y (gen-z?) have any clue of her significance?

We've got four pokemon now, anyway; totally oversaturating the game with pokemon love for her to return IMO.