What do you mean by multiple companies? Wasn't it only Sora Ltd?
That, and some other company I forgot, plus a few minor companies. Yeah, I know I'm pretty vague, but I think the same number of people worked on SSBB and SSB4, or slighty less worked on SSBB. I mean, it make sense. One company can't make something as big as SSB.
I might be wrong, but I am inferring it.