Dark Samus
Now if this theme isn't enough to convince people, then I don't know what will.
Chance: 5%
The Metroid series is one that, like Zelda and DK, hasn't recieved any new fighters in the last game and has had requests for one for some time. Ridley is without a doubt the first one most people think of when it comes to Metroid representation due to his legacy lasting as long as the franchise itself. However a big part of Metroid's legacy is also the Prime Trilogy, largely considered to be one of the best trilogies in gaming. And while Ridley does make a few appearances in an antagonistic role in the Primes, Dark Samus is actually the primary antagonist of the trilogy and would act as the best representative of the Prime series since she is indeed the titular character, Metroid Prime.
When thinking of Dark Samus, most would simply think of something like Dark Link (colour swap) or Dark Pit (1:1 clone) and while being a clone of Samus is a possibility due to having an almost identical body type, it would actually be a less than appropriate way to incorporate the character in Smash since it wouldn't really take advantage of her phazon abilities which is where her remarkable moveset potential would come into play.
Unfortunately her best chance of being added was during Brawl when the Prime series was in fact in its prime. Coming off of Prime 2 with Prime 3 on the way. And in Smash 4 she was merely added as an assist trophy instead of being playable.
But the ultimate hindrance she faces isn't other Metroid characters or her moveset potential, it's ultimately relevance. The Prime trilogy ended over a decade ago along with Dark Samus being canonically dead with confirmation from devs that there's no plans to bring her back. After the announcement of Federation Force it was confirmed by Tanabe that he was done with the whole Phazon arc and the story of Dark Samus. And while Metroid Prime 4 is confirmed to be a real thing, Dark Samus's involvement in the game directly is not likely...in fact the only way I can see her be implemented is if it has a Hunters like multiplayer and Dark Samus is a secret playable character or something (which would be ****ing amazing btw!!!). Or of there's some sort of plot twist that revives Dark Samus in some way.
With Dark Samus being too late, and Sylux likely being too early, my current stance on Metroid representation is Ridley or no one. Sakurai doesn't usually add characters just for the sake of representation with a few exceptions from games like Pokemon and Fire Emblem mainly due to the nature of those games. And unfortunately due to the nature of the Metroid series Smash contenders are few and far between.
Want: 100%
Easily my second most wanted fighter for Smash with Midna being the only one I would prioritize over her. On the surface Dark Samus may seem like a boring choice especially with two forms of Samus already in the roster, but rather than just being a straight up clone she's actually a very powerful form of a Metroid that has taken control of Samus's Phazon Suit. She's a bit of a special case compared to other Nintendo Dark doppelgangers. Her abilities as Metroid Prime, as well as her manipulation of the toxic phazon substance being a primary plot device in the Prime series, Dark Samus could make for a very unique fighter. I believe that if she'd become a playable fighter she would share very little with Samus in terms of moveset, perhaps a missile shot or a different form of her screw attack but that's about it. Her appearances in game has her utilize a lot more than what Samus can use (though she is still capable of some of that but honestly that just adds to everything she can do that Samus can't).
Dark Samus is easily one of my favourite villains in gaming, she's one of Samus's most powerful adversaries and one that doesn't have the same size issues as yet another famous metroid villain. She's well established as the main antagonist of the Prime trilogy which is my personal favourite series in gaming. With the first game, Metroid Prime, being my favourite video game of all time (needless to say my expectations for the upcoming Prime 4 are high).
I'm still perplexed why she wasn't added in Brawl as a playable fighter because she was about as relevant and relevant could've been with Prime 2 being a very recent title and Prime 3 being on the way shortly after Brawl was released on the Wii. And with how critically acclaimed the Prime series was (and still is) adding a character designated to the series just made a whole lot of sense at the time. Unfortunate as it seems her time has passed and as much as I don't want to admit it she's very unlikely as an addition, especially considering how much she gets overshadowed by Ridley these days.
But for those who say they'd rather Ridley first, I have just one thing to say about that.
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Sylux
Chance: 1%
There is promise of some sort of future for this mysterious hunter. A somewhat major role in a spin-off with mixed reception as well as minor post-game teasers, hardly even qualified enough to be cameos. I don't particularly think either of it's appearances thus far have really given it a strong enough presence to be a contender for Smash as of yet.
Sylux could be a possible candidate for DLC if Prime 4 gets released in a good enough window. But as for the basegame I wouldn't bet on Sylux having a very strong presence in Smash whatsoever.
Want: 10%
While I don't really have anything against Sylux as a character. I'm also still not totally sold on the idea either. Without a doubt in my mind both Ridley and Dark Samus both have enough of their own merits to be playable fighters in Smash. Sylux just sort of seems more of the 'well if we can't have such and such then I guess...'
It also doesn't help that Hunters was actually one of the few Metroid titles I did not enjoy. In fact it's probably my second least favourite Metroid title behind Other M. So it's appearance in that game (which was no more significant than the other 5 hunters I might add) didn't really leave a strong impression on me. And of course teasers aren't enough for me to sell the character unlike many other people. Don't get me wrong I'm very excited for Prime 4 and how Sylux could be utilized within the game, it'd be interesting if Prime 4 was the start of a new trilogy of games and Sylux was a constant threat throughout.
But until then I'm in a wait and see mindset.
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Decloned Dark Pit-6.7%
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Lara Croft x5
Once Lara's day comes (which doesn't seem too far off) I'll probably be done with rtc.