Medusa from Kid Icarus Uprising
It's so rare to find female villains and while she was downplayed in uprising after Hades she is still an extremely fun baddie as well as the big bad for the first two games. Medusa has this awesome commanding evil lady presence and so much potential as a moveset. She could summon minors, use evil versions of Palutena moves, take attacks from her bossfight, steal moves from Hades, there is just so much goodness to be used there. In addition they could add a Hades guidance as a counter to Palutena’s guidance that Pit has to Hades could still be included with funny lines about every character. I think it be a dream come true to have her included and she really stands out among many of her peers in gaming as one of the definitive badass evil ladies in games.
Jack Frost from SMT
Shin Megami Tensei has been with Nintendo on and off since it was just Megami Tensei. The franchise was on the freaking Famicom, snes, virtual boy gameboy, gba, ds, 3ds, Wii U, and now SMT5 is coming to switch. The series has one Mascot and that's Jack Frost. The cute little dude would be a great way to represent the whole of the SMT series and be a cute interesting character. Jack could have different demons helping them with their attacks in particular the other Jack characters like Pyro Jack could be a recovery move floating Jack Frost back up while shooting fire above him.For a final smash Jack could fuse with the others turning into Black Frost as a transformation smash where all the moves are stronger and they are bigger now.
Elma from Xenoblade Chronicles X
Ima be real the designs in Xenoblade 2 are wack as fuck so I think Elma from X would be better further representation then any 2 character could be. Despite being on the low selling Wii U it's not unlikely that we get an X 2 on switch since it ends on a cliff hanger. While in X you play as a create a character Elma from X is a badass dark skinned woman who could really add new gameplay as well as diversity to the roster. Beyond this she is central to the plot of X and likely X 2 so she could be future proofing the roster. Her fighting style has her two wielding guns but she could very easily also use other weapons from X since Smash has never been opposed to changing a character from how they work in canon. Her final smash would be amazing too getting into a really cool mecha and slicing people up for a set limit of time.
Impa from Legends of Zelda
Impa has been in almost every Zelda game and represents both the action and magical sides of Zelda in ways Zelda and Sheik doesn't. Impa got to be a total badass in both Skyward Sword and Hyrule Warriors, I personally would love to take the Hyrule Warriors design with the giant sword and fuse the magical focused fighting from Skyward Sword to make her this big damage but speedy character. Legend of Zelda being such a big franchise there is always so much to reference in terms of movesets and Breath Of the Wild did a lot with the shekia so there is always ways to infuse that as well. I just really think that if we get a new Zelda character Impa is the most worthy.
Lyn or Anna from Fire Emblem
I know Fire Emblem has a lot of characters in Smash but most of them are clones and all but Lucina are default male. Fire Emblem is a series that while still rooted in misogyny, like everything in the games industry, managed to produce some of my favorite female characters ever. I propose Lyn or Anna because Lyn is the most popular female character in the series according to many popularity polls and already is an assist trophy in the game and Anna because she is in almost every Fire Emblem game meaning she will always be at least a bit relevant. Anna is one of the three free characters you get in Fire Emblem heroes the wildly successful mobile game and there she wields an axe and fans of Fire Emblem would be happy to see a Fire Emblem character finally not using a sword as a weapon. Along with that she could use her cloning gimmicks from Fire Emblem Warriors and use references to being a secret shop keeper throwing weapons out from a bag or something with random effects. Lyn would focus on a rapid fire attack fight style and add bows into her moveset since her promoted class has them in addition to her legendary sword. Lyn would be an extremely aggressive character ready to be in the opponent's face all the time but not able to take hits very well.
Dixie Kong from Donkey Kong
I believe Dixie Kong is a perfect edition for the games, while King K Rool is the most popular new Donkey Kong pick, Dixie has been the lead in Donkey Kong Country games as muchas DK since they are both playable in tropical freeze. She is a major female character and one who I really loved growing up and let me play as a girl when so few series did. Dixie has her hair and flying ability that set her apart but there is a slew of moves from across the Donkey Kong Franchise that aren’t used by any of the Donkey Kong characters currently in. She could jam out on her guitar, she could use Tiny Kong’s abilities from Donkey Kong 64, she could do so much to make her just this really fun character to play as who stands out.
Decidueye from Pokemon Sun And Moon
I feel like baring the next generation being announced and coming out before a Smash port ( and that is very possible) Decidueye is the most likely new addition. We got a fire starter in Charizard, we got a water one in Greninja, so we need a grass starter now. Decidueye would have extra sources of places to pull moves from since they are in Pokken Tournament as well. Decidueye has a really cool design, being an archer their gameplay could be very ranged based while having a lot of cool up close pokemon moves to reference for their normal moves. In addition being part ghost makes Decidueye able to potentially have a cool phasing out move or something like that to reference their immunity to physical attacks.
Eevee from Pokemon
So I know two more Pokemon in the massive list of Pokemon is overkill but Decidueye was my rational choice where Eevee is my passion choice. I think Eevee deserves to be in the game, they are a pokemon every generation I hope gets a new form, they are a pokemon with a massive following and they have to rank at least collected among all their evolutions in the 10 pokemon ever if not the top 5. What I want to see is a transforming eevee, Pokemon Adventure ( or Pokemon Special in Japan) had an Eevee that was experiment on by Team Rocket and could switch between it’s evolutions on the fly to attack. I would take to take that idea and make an eevee that could do the same but now with it’s additional eeveelutions. Custom moveset could be used to change what eevee evolutions you become with your special moves or they could be mixed in with your standard moves. It’s a great way to have a ton of popular pokemon built into one.
Cali and Marie from Splatoon
While the popular Internet speculation is for Inkling to be added to the game I want Agents 1 and 2 aka Cali and Mari to be added in. They would keep the game fresh while actually having an iconic look. Pearl and Maria can be background characters performing in a splatfest stage. They would spray ink on the ground and both be active on the field at the same time. They would perform joined moves similar to the ice climbers only you can swap control of them to make focused use of one’s B moves that differ between the two. They would be an amazing way to include one of Nintendo’s new biggest franchises while promoting the staple characters. Their area control and ranged based gameplay would make them fun additions to the roster that are all about not getting hit and not getting too close.
Sami from Advance Wars
I will fight for Sami to be added to Smash with like my dying breath, every time I make a list she is number one and she will continue to be number one. Advanced Wars Dual Strike is one of my favorite games, it is just such a blast to play with or against friends building armies and tactical thinking. The story modes are fun and simple and I always was in love with Sami even in the earlier games. She is the leading female character of the series with some of the best gameplay mechanics and she would very clearly be the most interesting character from the series as a playable character given she carries a gun in her key art and is focused on making the ground troops stronger. Sami’s normal attacks would focus on her just attacking and would be pretty weak but deploying her specials summon little advance wars sprites units that attack with you shooting their little sprite guns. She could have this really unique summoning moveset that takes ideas from both King Dedede and Olimar.