I'm not sure if I should consider any of this crow eating because these were either things I had written off in my head or didn't even think about the possibility of, and for either case wasn't particularly vocal or adamant about it.
1. Back in 2012, when Bayonetta 2 was announced, one of the first thoughts I had was that she had a chance to be in Smash 4. She wasn't in the base game and that kind of killed my hopes of seeing her, as she might have been considered too inappropriate for Smash. I still voted for her in the Smash Ballot, but I had pretty much written her off as not happening.
Lo and behold, the #1 character I personally wanted to see in Smash comes out of the full moon, and it was glorious.
2. Wii Fit Trainer and Villager were both ones I filed under the "didn't even consider it" category. Villager was based on Sakurai's comments in the past about there not being a good way to implement an AC character. Wii Fit Trainer was just simply so out of left field that I honestly didn't even think about it, but then when she was announced it made total sense.
3. I expected Chrom too, but I was surprised and much happier to have Robin. It was cool to get our first FE character that used magic and actually brought in FE mechanics of weapons degrading and being used up.
4. Corrin was also under the "didn't even consider it" category, mainly for the obvious reason that we had a lot of FE characters already. Corrin turned out to be the character I didn't even know I wanted. She looks really interesting to play, and has mechanics that have never been done on a fighter in Smash, particularly that stab move where she anchors into her opponent.
5. Ryu was also under the "didn't even consider it" category. I don't really have a good reason for why I never really considered Ryu, the thought just never crossed my mind. I was definitely pleasantly surprised though.
6. I had mostly written off Mewtwo, Lucas, and Roy. Mewtwo and Lucas I wrote off because they were trophies in the 3DS version. Roy I didn't really see coming back just because he was mainly for the game that came out around the time of Melee. I was glad to see Roy come back with moves that differentiated him even more from Marth and Lucina.
7. I never really considered Cloud either. If there was any FF/Square Enix character, I thought it would be maybe Cecil, Kefka, Black Mage, or Sora from Kingdom Hearts. Cloud was out of complete left field, but I'm glad we got him. He's pretty much the face of Final Fantasy, and usually the character people think of when talking about FF in general (not any particular game in the series).
8. Greninja I really liked, but also did not see coming at all. I actually did not even think a gen 5 or gen 6 Pokemon would get in, but Greninja is cool and has a unique move set.
I was never particularly vocal about any of these, but all of them really surprised me in a good way. Smash 4 has a dream roster that is truly impressive. I honestly don't know where Sakurai can take it in a potential Smash 5. I mean the game is basically at the top right now since Cloud and Bayonetta are in the game.