It's mostly just an ESRB problem, as this whole issue is because of a new ESRB policy that bans games from referencing other games of a higher rating, something CERO doesn't have. It's created a lot of issues for Smash, such as Mii costumes from primarily M-rated franchises not being allowed to list what series they're from in Smash reveal trailers and now the 13 Sentinels, Noah and Mio, and Zagreus Spirits do not even list what franchise or game they were from, a first for Smash. And it's an issue they have to address or else they will be severely limited in what characters they can add and they would be forced to completely cut certain franchises from Smash like Metroid, Earthbound, Xenoblade, Fire Emblem, and more. They would be forced to either elevate Smash itself to a higher rating or completely stop releasing the series in North America entirely.