Nobody took Rosalina as a serious option either until she got revealed. I should know; I tried making a case for her being an option for a goddamn speculation chart and got a LOT of pushback. She wasn't Toad or Bowser Jr. and "They would never add her before Daisy."
Guess she's a "surprise character" too.
Same with Robin and by extension Lucina. Thinking anyone
but Chrom had any sort of chance? Let alone the avatar character? HA! You must be joking.
"Surprise characters".
And don't even get me started on Greninja. No one had a consensus on what Pokémon from X/Y was coming but one thing was certain; "a Starter Pokémon will never be without a Trainer". No one saw a solo Greninja coming. And it's not like Greninja had any sort of stardom at the time either to make it make sense.
"Surprise character".
Hell, no one actually predicted Villager either, especially not after it was made clear that someone like him would "never" be in Smash since Sakurai said it made no sense for them to fight, along with Nintendog. And those that were still advocating for an Animal Crossing character regardless all banked on Tom Nook.
Oh hey, Villager's a "surprise character" too by definition.
Oh look at that, Smash For actually has at least SEVEN "Surprise Characters".