Why do you even want to make a push to start with? All it's going to look like is a spam day for a character, and it'll turn it into a Waluigi kind of cause where nobody believes in it anymore. There is such a thing as too much begging for a character. And then anybody can google and find this thread where it's obvious that it's not a large number of people that support the character, but a very few "insisting" people that keep posting about it. Especially when you start gathering fans for other characters and try to have all of them support your own, by supporting theirs. That's playing with the numbers, very blatantly, and not an actual manifestation of interest.
And Skull Kid has a chance I think, so don't go ruining it by abusing such tactics. Unlike Geno, that most people know only because of the hype train (let's be real, he was only present in one game that has not been remade since), Skull Kid has reached a level of recognition to the point that they added Mii costumes for him in the game. And there are still fairly recent and available versions of the games he's in.