https://www.youtube.com/watch?v=sen_43HXOd4
Stumbled across this interview with Xander Mobus, the announcer for Smash 3DS/Wii U. Pay close attention to the question at 17:42.
Basically, Xander says he didn't know the full roster of the game because the script had red herrings, as in, characters he had to announce their names, but weren't in the game. He didn't believe Duck Hunt was meant to be an actual character.
The producers did so to avoid full roster leaks.
@
PushDustIn This will definitely interest you.