I think there's a number of reasons we won't see those anime/manga characters in Smash. Firstly, they're anime manga characters. In the case of Ash, we already have Pokemon Trainer, so it'd be redundant anyway. But I'm also going to guess that TPC wouldn't sign off on one of their human characters hitting a Pokemon. They're already pretty sensitive to that angle. And that would relegate any human characters to a Trainer-like role anyway. And who are Jessie and James going to use, Arbok, Weezing and Meowth? Honestly, we'd probably just get Meowth without all that other stuff.
And if we were going to get Meowth, truthfully, it would've happened a long time ago.
But yes, Ash is undoubtably the most iconic non-eligible Nintendo character. And he's probably one of the most well-known gaming-related characters not playable in Smash. Though I would suggest Ms. Pac-Man, Master Chief, and that Space Invader sprite as right up there as well. And those guys are all eligible, which helps.
Nintendo also published Ultimate Alliance 3, that doesn't make Spider-Man eligible. Nintendo publishing a game doesn't make that property gaming in origin, and the eligibility of characters created in a game of an established non-gaming property isn't clear cut.
But you're completely creating the entire impetus Nintendo will feel compelled to represent a toyline in their video game about video games. That's an imperative which in all likelihood, won't arise. To lend Chase any sort of actual merit, you have to create a narrative wherein Nintendo wants to put Lego in Smash, despite zero evidence of them caring about non-gaming properties in the Smash context.
If they suddenly want to start putting properties that didn't originate as video games in Smash, I don't expect they'd even bother upholding the "must've debuted in a game" rule.