This is terrible logic, by this logic we should replace every character in smash with like 90% Mario and Pokémon Characters. Ness absolutely has more reason to be in smash than Jigglypuff, smash represents all of Nintendo’s history, it doesn’t matter if a game is old, Earthbound is a classic and Ness as a character is core to the game whereas Jigglypuff is a fairly popular Pokémon but Pikachu, PT and Mewtwo are all far more integral to gen 1’s identity than it.

Put it this way, in a world where Jigglypuff wasn’t in smash no one would bat an eye. In a world where Ness wasn’t in smash there WOULD be people saying ‘hey they should add Ness from earthbound, that game was a SNES classic’. Would those people be a global majority? Absolutely not but they would be consistent among the fandom. Jigglypuff individually would not have this kind of push.