As a random conversation starter, I'd like to point out a few things about the Villager. Notice that the reaveal trailer shows a town with objects that debuted in Animal Crossing: New Leaf, or in other words, the newest game. In the picture for the Villager, Isabelle is present in the background, etc...
Basically, what my point is, is that recency appears to have some sort of influence. However, i'm not saying it's a major influence, or has decision making powers with characters. All i'm saying is it's there.
One other thing is that the Animal Crossing stage is taken from City Folk, so my suspicions that Smash 4 is taking things from the previous generations (as previous Smash installments has) has been confirmed thus far.