An interview with Sakurai
http://www.nintendolife.com/news/2014/10/exclusive_masahiro_sakurai_on_planned_accidents_and_new_ways_to_play_super_smash_bros_for_nintendo_3ds
"In actual fact, since the development team is different for this game as compared to previous iterations, even the veteran characters were remade from scratch. Although this meant an increase in costs, it is precisely because of this and - in no small part - thanks to the efforts of the development team, that we were able to put so much content into the game."