Even though this has probably been done before, I wanted to share my ideas for a possible Smash-Moveset for Shantae.
It will mostly focus on the original game, with some stuff from the later games.
None of my movesets will include the Pirate's Gear, since everyone seems to use them for their moveset suggestions.
I have different movesets, depending on how her transformations are used.
But I will start with the attacks, that would be the same for all movesets.
Jab: Hair Whip
D-Tilt: Crouching Hair Whip
Both come straight from the Shantae games, as her signature attack.
Her Hair Whip has less range than Simon's Holy Whip, but is faster and can be used in rapid succession.
Each hit knocks the opponent back a little, making infinite combo's impossible.
S-Tilt: Roundhouse Kick
Shantae's Kick Attack from Pirate's Curse.
U-Tilt: Rising Kick
Ground-Version of Shantae's "Rising Kick" from the first game.
Dash: Elbow Charge
Another "Fighter's Gear" move returning from the first game.
Grab: Hair Toss
Ties up the opponent with her hair.
Pummel the opponent with knee strikes and then simply toss them with your hair in any direction!
N-Air: Tiara Spin
Spinning Attack, hitting in all directions around her.
Just like the same "Fighter's Gear" move from the first game.
U-Air: Aerial Rising Kick
Same as her U-Tilt but in the air.
Resembles her "Fighter's Gear" move more closely (except it doesn't lift her up)
D-Air: Drill Kick
And the last of her "Fighter's Gear" moves from the first game.
The Drill Kick works pretty much like in said game, except it's faster and goes straight down (not diagonal down, like in the actual game).
Of course, it can be used to spike the opponent.
F-Air: Forward Spin
Hits forward with her hair, while spinning.
B-Air: Backflip Kick
Exactly what it says on the tin.
Neutral Special: Fireball/Flash Bolt/Flamethrower
Fire a Fireball projectile forward. Can be charged.
Middle Charge turns it into the Flash Bolt from the original game, firing three projectiles.
And at maximum charge it becomes the Flamethrower attack, that made its debut in Risky's Revenge.
Side Special: Storm Puff
Sends out a small cloud, moving into a direction of your choosing and letting out a couple lightning strikes on its way before it disappears.
Can be delayed by holding the button or cancelled by Shielding.
And that covers the attacks, that would be the same for all movesets I have thought up.
Now for the interesting part...
I have two possible movesets, using her transformations in different ways.
Moveset 1: Smash-Transformations
The simplest way to use Shantae's Transformations, is to use her in Smash and Special Attacks.
She quickly transforms into her forms for the attack and then reverts right back after the attack.
And so, the attacks are as follows:
F-Smash: Monkey Bullet
Changes into a Monkey and performs her Monkey Bullet.
Reaches further than normal Smash-Attacks, but has less knockback.
D-Smash: Elephant Stomp
Changes into an Elephant and performs a stomp-attack, causing a shockwave that hits opponents around her.
U-Smash: Spider Web
Changes into a Spider and fires a Spider String upwards.
If it connects, it grabs the opponent, slams him into the ground and launches them upwards.
Up Special: Harpy Flight
Changes into Harpy Form, allowing Shantae to fly freely for a short time, before the transformation runs out.
Pure Recovery Move!
Down Special: Pike Ball
Shantae uses three Pike Balls flying around her, blocking projectiles and dealing minor damage to opponents on direct contact.
The Pike Balls have limited hits. After a certain number of blocked projectiles or direct hits, they will disappear.
Shantae can also throw the Pike Balls in an arc, by pressing the command again, while the Pike Balls are up.
Moveset 2: Special-Transformations
This moveset is more faithful to how the transformations work in the games, but is also a little more complex.
F-Smash: Power Whip
A powerful Hair Whip Attack with more range and power, but only single hit.
Yes, that means her hair grows longer during an F-Smash.
Referencing the upgrade from the games, that makes her hair longer, giving it more range.
U-Smash: Ponytail Arc
Swings her hair in an arc upwards, covering a wide area above her.
D-Smash: Pike Balls/Fireballs
Uses Pike Balls to hit opponents on both sides.
At maximum charge, it becomes the Fireball Item from the first game!
(FYI, in the first game, the Fireballs weren't a projectile, but rather an upgraded Pike Ball)
Up Special: Float Muffin
Launches her into the air, while also ramming anyone in her way.
Down Special: Transformation Dance
This is where the complex part of this moveset, comes into play.
Holding down the button will make Shantae start dancing.
While she dances, you have four transformation-options. Monkey, Elephant, Spider and Harpy. (The original four!)
Each Transformation is tied to one of four directions. Like Shulk's new Monado Art Wheel!
Pressing the corresponding button, allows you to turn into said form.
To stop dancing, simply let go of the B-Button without pressing a direction and you cancel the move without transforming.
You can only stay transformed for a limited time.
If you want to revert back into Shantae, before the time limit is up, press Down-B again.
(The Transformations are timed, since I fear they might be very exploitable, even with the weaknesses they have.)
Transformations excel at different roles, but their movesets are very simplified.
They have no Smash Attacks or Grabs. And they only have a single Special Attack (Two if you count the reverting back to Shantae).
This is because making full movesets for each and every form, would be a very daunting task.
With limited and simplified movesets, I figured the transformations as specials, would be more realizable.
Monkey Form
The Monkey Form excels at swift attacks, that don't hit very hard but are fast and can rack up damage quickly.
A unleashes quick, rapid attacks with the Monkey Claw. And B allows you to leap forward with the Monkey Bullet.
You can even direct it!
The Monkey Form is small, but also very light. Meaning it can be knocked off very early!
Elephant Form
The Elephant Form may be very slow, but it hits very hard.
Perform a ramming attack with A and a Stomp-Attack with B, with a rather wide range.
You can even damage opponents simply by landing on top of them.
The Elephant Form is powerful and also a tank. Due to its weight, it can take quite a lot of punishment.
But it comes at the cost of pitiful air capabilities, very low jumps and worse recovery options than even Little Mac.
Spider Form
The Spider Form is a trickster, excelling at zoning.
Use your Spider Venom with A to hit opponents from a distance and use your Zip Line with B.
You can direct the Zip Line and do lots of things with it.
If you hit an opponent you can throw them.
If you hit the ground, you will make a spider web, that lasts for limited amount of time, slowing down opponents that walk into it.
And if you hit a wall or ceiling you can stick onto them.
You can even use the Spider Venom from these positions!
However, the Spider Form is rather weak in close-range combat. So keep your distance!
Harpy Form
The Harpy Form excels at aerial combat. Having multiple air jumps.
Use your Talon-Attack with A and use a spinning attack with B. Keep holding down B, while in the air, to glide for a limited time.
Her Recovery is phenomenal for obvious reasons.
The Harpy Form is swift and strong in the air. But not so much on the ground, where she is slower.
Also, while not as vulnerable as the Monkey Form, she can still be knocked off a little easier than normal.
And here we have the two possible ways the transformations could be handled.
Which one do you prefer? Or do you have a better idea?
As for her "Final Smash"
Either "Dance Parlor", "Obliberate" or "Friends til the End"
Enough said.