The main inherent rule that seems to be present whenever a Smash Bros. game adds a third-party character is that the character, or at least the character’s series, has been, or is soon to be, on a Nintendo console at any point, for any game. In the case of Joker, it was related to Persona spin-off games since Persona 5 still seems to never be getting a Switch port at the moment, but of course it gets a Warriors spin-off on the system, like so many things get now. Yet the SMT series proper is still often at home on Nintendo systems. While I’m still fairly sure that no Halo game has been on a Nintendo platform to my knowledge, Minecraft has been on at least three of their consoles. As a bonus, it also fits a second possible criteria that the game or series has to have made a significant impact in the world of video games, and that game has certainly been around long enough at least. I’m also not sure that Goku counts as a video game character as well. Then again, Nintendo overall drives the game and can break all the rules they want with it, provided it doesn’t result in major legal issues. As far as breaking things, apparently Twitter broke with the announcement, but unfortunately I don’t think it stayed broken.
Smash is full of weird characters with different playstyles, to where even new mechanics show up for some characters. Trying to convert a building block simulator into a platform fighting party type game definitely sounds difficult. As well, the character is pretty much just considered “Minecraft” since it has four named variants, which probably amounts to two skins per variant. Interestingly, the normally tall Enderman has been shrunken down a little to fit the same hitboxes as the main Minecraft player model, so we have a short Enderman, or maybe more like an Enderman player skin. Any future characters are really up in the air as far as possibility. As long as they don’t try to have a character based on that one Epic money pit that’s also making gaming history in a different way, the most disappointed I could probably be is if they add in the 20th Fire Emblem sword user that’s also Fire/Fighting type. Then again, I’ve still yet to buy any character packs, because I believe in seeing what something has before buying it if possible, especially when it comes to DLC.
Still, Microsoft has been playing nice as far as letting some of their owned properties exist in a Nintendo game. This generosity might extend to letting future Bethesda games exist on a PlayStation, unless they feel the need to pull back on Sony and decide that they’re not getting those games to force an advantage for the Xbox. In either case, they’d potentially profit from the games in either case, like how Sony may profit from game disc sales or of consoles with the drives using the Blu-Ray format due to licensing and such.