If it feels like I come down hard on some moveset ideas, it's just a matter of personal experience with this game's newcomers. Fans get all excited to try them out and see how faithful or unique they are, then after about a month or so the magic fades, and unless the character happens to be at least somewhat effective competitively, the praise gives way to grousing about their shortcomings and how they're actually poorly designed, no matter the faithfulness.
I've heard everything from how Simon's weaknesses in close combat and recovery are disservices to his character, even though anyone who's played a classic Castlevania would know the pain of being unavoidably knocked into pits by small annoying creatures. Complaints about K. Rool being slow and clumsy when he's never been shown to be particularly graceful or bright (smarter than Kongs is not a high bar), or Ridley's big size and lack of defensive options to get out of trouble, despite never using any sort of defence beyond pure aggression and maybe armor in his games.
But Shantae in particular could have a worse problem than just not being very good; being almost completely overshadowed. If her transformations, say, make her something closer to Pokemon Trainer, but more complicated and nowhere near as effective, well... you know. It won't matter how faithful such a system happens to be in the context of Smash.
Because of all that, when coming up with movesets I try to make sure they are at least functional and effective on a basic level, using the source material as inspiration wherever possible but deviating as need be if it proves detrimental in a Smash context. Just bringing a character over as-is for the sake of accuracy won't cut it in this age.