And why does it have to be Pirate's Curse's design and nothing else?
I honestly can see a design based on her Original game or Risky's Revenge, working much better for Smash.
And like I said before: Despite its popularity, I don't think basing Shantae on Pirate's Curse would be a wise move for Smash, where part of adding a character, is introducing said character to a new audience.
And Pirate's Curse, sorry to say, is the absolute worst representation of Shantae as a character.
All other games in the series, represent her much better.
For the simple reason, that she is actually using her own powers and abilities in these games.
Whereas in Pirate's Curse, she pretty much is Risky Boots in gameplay.
I get the popularity of Pirate's Curse.
But she isn't using her own powers in this game.
And me personally, I don't think Sakurai would base her on Pirate's Curse, simply because the game is more popular than other games in the series.