jigglover
Smash Lord
Little Mac was incredibly popular leading up to smash 4, so it made sense to show Mac's stage first - just as a little nod to the series. Paper Mario isn't on the same level as that lol.Boxing ring was shown off first, Little mac confirmed later on. Mario galaxy stage shown first, Rosalina confirmed later on.
BUT if sakurai were to hint at Paper Mario being a playable character, he would of just teased about this stage and not call it by its franchise name. He could of questioned about the paper environment and leave out the paper mario stage bit. Keep in mind guys, the Boxing Ring was never mentioned as A Punch Out Stage. It was hinted to be Little macs stage since he is a boxer and his games take place in a boxing arena (and in NY while your in a pink training outfit).
Mario Galaxy could have easily just been Mario's stage, as it was the first one shown off IIRC. Who here actually went "Wow Mario Galaxy stage Rosalina confirmed!"? No one, because having Galaxy as a Mario stage made sense for the characters of Mario and Rosalina.
Paper Mario stage is just blatantly from the Paper Mario series. I can't see a character coming from this.