Just thought I'd jump in with a clarification of copyright law. I am not a lawyer but this has been an area of professional interest. It boils down to the fact that game mechanics can't be copyrighted. So long as you don't use art, sounds and text that infringe on someone else's copyright then you're fine. There is also trademark but that gets murkier but I don't see an "Italian" Plumber declaring it's-a-me so I don't see a trademark breach either.
This game, while a blatant clone, does not appear to use any assets owned by Nintendo and Nintendo can't copyright the mechanics of Mario or Mario Maker. I can't see anything that breaches either the word or spirit of copyright law.
The fact that this was develop in China also doesn't factor in. This could be developed anywhere and still would be legal, the main reason this comes out of places like China is that they seem to have an industry built around cloning successful games.
Now, whether you think this is creatively bankrupt, ethically OK etc. is a completely different matter, but Apple can't shut this down on any legal claim (though terms of service they could just reject it) and Google.... Google doesn't care what gets put up on the app store as long as they aren't going to get into trouble for hosting it.
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