PrinceGal3n
Smash Journeyman
I'll give it a shot:
1) Doom Slayer
I mean, with Doom being such a big point in gaming history, it would make sense! And for those who say that he'd be too violent and gory, they could use the blood effects of the old Doom games to be within boundaries.
2) Buzzwole
This titanic Ultra Beast is just as powerful as he is popular. He could be unique in the sense that he could drain energy from his foes to increase his attack power! He'd be perfect!
3) Decidueye
With him being in Pokken DX and the first in his evolutionary line being the most popular Alola Pokemon, Decidueye's chances are pretty high.
4) Spring Man
ARMS was an amazing game, and although a lot of people would prefer Ribbon Girl, Spring Man alone has more unique properties than Ribbon Girl (I mean, multiple jumps were given to Pit/too, all Kirby reps, Jigglypuff and Charizard), which include his perma-charged ARMS at low health (or high damage in this case), and a deflect wave.
5) Elma
I've only seen gameplay of Xenoblade X, but I think Elma would be perfect for this game for her ability to change between short swords and pistols! Not to mention, her Skell would be a perfect Final Smash.
6) Rex and Pyra/Mythra
Xenoblade 2 was fun as hell for me, and I believe the Driver of the Aegis would be pretty unique himself, he'd be nowhere near similar to Shulk! Also, I believe that for Rex, they could give him a mechanic that I won't spoil for those who haven't gone that far into the story. (Those who don't know would feel it's all Greek for them, but those who did probably took their breath away and would put the spirit of the character!)
7) Labo
Nintendo Labo looks to be in development since just a few weeks after Smash Bros 4 DLC was fully released, and tbh, Labo would be a perfect WTF character. Maybe he could be a cardboard recreation of the robot who'd use other Toy-Cons in his moveset, or it could be the Laboman that's popular on Twitter right now.
8) Bandana Waddle Dee
With Kirby Star Allies having Bandana Dee, as well as Waddle Dee being the most iconic Kirby enemy, this little guy has quite the following. I remember playing as this guy in Kirby's Return to Dreamland, and he seems like an extremely fun character to implement into Smash Bros.
9) Ridley
The space dragon of the Metroid franchise has been chopped liver in the Smash Bros. franchise, but until recently, I've gained more hope for this monster than I had before. I'm very confident that this guy would be in Smash, and he has potential to be unique. I saw one concept that really caught my attention. This Ridley concept gave him three stances: a quadrupedal stance which gives him a crouch, faster movement speed and the smallest size but less attack speed and attack power, a bipedal stance that gives him faster and more powerful attacks but removes his ability to crouch, slightly increases his size and reduces his speed (Both stances would change using the Down B of this moveset), and an aerial stance (Accessed using Up B) that gives him a spread-out in his attacks, high air speed and free movement, but this stance has a time limit, his attacks are less accurate and an enormous size. Honestly, when I saw that, I thought it was raw genius!
10) Takamaru
He was obscure once, but eventually he seems to have gained popularity thanks to his Assist Trophy status in the last game, his game releasing in 3DS Virtual Console and his appearance in Samurai Warriors 3. I feel like Takamaru's chances are quite high here.
Where did you find that concept of Ridley? I like the sound of it!