So with Captain Toad's deconfirmation I was thinking... there's no other Mario character left deserving of a spot in the roster. Only Captain Toad, Daisy and Waluigi would seem logical inclusions to me, and Daisy was the only one who made it... as an echo. So, no new Mario fighter this time? Even though Captain Toad and Waluigi are immensely popular and probably did fairly well in the ballot?
There are two explanations: there will not be any new Mario fighters (in Smash 4 we got both Rosalina and Bowser Jr., and the comeback of Dr. Mario, so Mario has already a good number of characters)... or Sakurai is leaving Mario's newcomer spot to Geno. That would explain why Waluigi is still a AT, two Mario newcomers would be overkill in a game which (presumably) won't have many newcomers, although to be fair we got 2 in one day along with 3 echoes.