I translated a small tidbit of information from Famitsu and the SSB4 section, that talks about the various forms of Master Core.
Today’s Famitsu didn’t have much, but this was the most useful page. While most information is known by now, it is good to see the exact requirements listed here rather than guessing:
This isn’t everyone, but it is all Famitsu has listed for now. Maybe the rest will be next week.
This is the only part of the page I translated, so I cropped it. The original is below my edit/translation as usual.