I'd like to see Professor Layton actually!
Ice Climbers was in the game but they didn't work on the 3DS for some reason. Sakurai-san said they couldn't debug the issues and had to drop the characters. They wanted the same characters in both titles and they wanted them all to play exactly the same, so when they were dropped from the 3DS they were also dropped from the Wii U. He said there were other dropped characters but didn't say which ones. They still wanted 50 characters so they had to cheat and split out some: Zelda-Sheik, Samus-ZeroSuit, Marth-Lucina (originally she was just a skin for Marth), Pit-Dark Pit (also originally just a skin). After splitting out the characters Sakurai-san said he liked the way they played on their own more, so he was happy with the move even though it wasn't originally planned.
I believe Sakurai-san commented on Daisy and said they didn't see her as having a very unique move set vs. Peach so she wasn't included. I still think they should have given Peach a Daisy skin and called her as such during character selection and victory pages, much like Alph.
Sakurai-san said that Ridley could not be a playable character because he is much larger and scarier than most playable characters. He said he would have had to dumb down Ridley to make him playable and that wasn't acceptable. This logic also applies to Ganon not being playable.