I have not played the wii U version yet but I have beaten the 3DS version and I am very curious of what the hell happened to the deadly six at the end because after you have the final rehash boss battles with them they don't show up in any cutscenes afterwards, I mean seriously they were the main antagonist of the plot and the story just seems to forget about them after you defeat them.
I really enjoyed these villains and I do hope they make a return though.