A handful of these characters, mainly the lower ones on the list, I admit are basically impossible. I'm probably only including them so that I have a list of ten... but I'll still justify them.
10. Liu Kang - Yeah, I know. A Mortal Kombat rep that isn't one of the two ninja icons. The thing is, Liu Kang was originally MK's main hero and protagonist even if he wasn't as well known as the two of them. If a Mortal Kombat rep was anywhere near the realm of possibility, I just think he'd be fitting thanks to Street Fighter's Ryu having made it into Smash as well; they're somewhat similar characters (and the two going against each other would be awesome to see). Besides, Liu Kang has traditionally been the sole non-violent fighter of MK as a Shaolin monk, so his identity doesn't revolve around blood and gore like almost everyone else. Even one of his Fatalities could be safely used as a FS without gore; either his Cartwheel Kick, Flaming Fist, or dragon transformation.
9. Spike - The player character from Ape Escape 1 back on the PS. No way this guy's happening, I admit; he's pretty unknown except to the most hardcore of Sony fans. But Ape Escape was one of the oldest 3D platformers I've played and the game has a special place in my heart. His moveset would be pretty cool; there's a lot to choose from with all the gadgets you have in the game.
8. Kitana - I know, another MK rep. She's just been one of my favorites from the series as a female ninja in blue that attacks with fans. She'd be a strong female character to include (if the sky was the limit) and, similarly to Liu Kang, doesn't have to be bloody and mature.
7. Lara Croft - To clarify: This would be the classic Lara Croft. The character from the first game up to TR: Underworld; NOT the rebooted Lara. Aside from me liking her traditional characterization and personality way more, Classic Lara is ironically more family-friendly than the modern character; her games weren't excessively bloody or mature, with the exception of Angel of Darkness which was a game with a lot of problems anyway. Only Underworld gets pretty serious. Other than that, she's a cheery heroine and could definitely fit in when Solid Snake's already been present. But she's pretty unlikely all the same; her franchise has had very little presence on Nintendo's systems, and she's now owned by Squeenix.
6. Lee Sin, the Blind Monk* - See character entry below.
5. Nidalee, the Bestial Huntress - Yeah, I'm listing two League of Legends champions. Now, please calm down, I don't think they're actually happening in the foreseeable future. They're both purely theoretical. Lee Sin and Nidalee are two of my favorite champions of LoL and if anything was possible I'd certainly pick them. My quick explanation for Lee Sin is basically the same as Liu Kang's, another martial artist like Ryu plus he's a pretty cool character with an interesting backstory. As for Nidalee, I quickly came to like her as a character because of how she's basically an homage to World of Warcraft's Night Elf druids, specifically cat druids and the Night elf race having feral, female warriors for their army. She honestly could fit into Smash especially if transformations were still supported as her gimmick is being able to turn herself into a cougar for melee combat, while in her human form she wields a javelin spear and has limited healing magic. She also has a really fun playstyle and personality in League that could easily transition over to Smash Bros. Also another strong female fighter.
4. Shadow - This wouldn't actually be a DLC character, not for this current Smash... but I want to bring him up. He'd be cool to see in a future Smash if he could get promoted from Assist Trophy. Should Sakurai design him correctly, he would just barely be a semi-clone of Sonic. He'd bring a lot of new things with his Chaos powers, and even his FS wouldn't have to be a copy; it could be a powerful, time-slowing Chaos Control with possible status effects added (dizziness, increased knockback, etc). Sadly, the downsides of Shadow would be him being similar in appearance to Sonic (and the same animal type) and would be slightly redundant as the second rep. Needless to say, the character's also a salt magnet.
3. Krystal - This is kind of an odd one for me because I'm not some kind of hardcore Krystal fan. I'm also not a furry. But I do think Krystal would be a nice additional rep for the SF series. Adventures, and to a lesser extent Assault, were mostly quality games that get somewhat unfair treatment. And I look at Krystal as a better character than just being "the token female"; she has a neat backstory and personality (in Adventures and Assault only...), she'd be an additional female fighter, and her moveset could be heavily based on Adventures, redeeming her lacking playable role in that game. However, like Shadow, she's a salt magnet ("ROFL ONLY FURRIES LIKE KRYSTAL") and her future for the SF series is up in the air with Zero coming out as a re-telling of SF64. I'd also wonder if her physical appearance in Smash would be a little odd... the SF characters are all very short, but in the SF games, Krystal kind of seems like she's tall. A Krystal the same size as the others compared to the taller characters might look weird, but that's just a minor thing.
2. Knuckles - Between Knuckles and Shadow, among my favorite characters of the franchise, I'd grant that Knuckles would be a better idea if Sega were to get an additional rep. He's one of the most classic characters, he's a natural fighter and it'd be easy to make a moveset for him. He could also bring a lot of cool/funny music to the game, and maybe even an additional stage. I also would want Knuckles to make it in because of the fact that he's been mostly abandoned by Sega (along with basically every other additional protagonist not named Tails); it'd be only fair for Knuckles to make a prominent comeback to being playable again even if it's in something like Smash. Sadly, even this guy has a major downside; if Sonic gets another rep, I have an uneasy feeling that it's almost guaranteed to be Tails. Because Tails is another classic, but has always been the "main sidekick" and is seen as the Luigi of the series (which is something I dispute, but whatever). I wouldn't mind Tails per se, but he would make me a little sad because of how it would mean that Knuckles wouldn't get a chance. I feel like Tails would thematically fit more as an Assist Trophy, especially since his role in his own series has diminished to being a voice from the sidelines.
As for the only character I'm really hoping could be given a chance and would be the only possible DLC I'm holding out for:
1. Shantae - Yes, this controversial choice.
I was introduced to Shantae by happening to catch a thread discussing her possible inclusion in Smash somewhere several months ago. Looking her up sparked my interest, and I found out that it was an "indie" platformer series that started with something of a cult following and grew into a pretty popular and beloved franchise. Curious, I eventually went and bought Shantae: Risky's Revenge having heard good reports about the games. The gameplay grew on me quickly, and the character herself was just so likable as a cute, female, half-genie. Bought the sequel, Pirate's Curse, shortly thereafter. I quickly saw why people were calling her perfect as a Smash character, and she's my vote on the Ballot.
Shantae brings a lot of things to the table: She's a dancing half-genie with hair attacks (along with basic hand-to-hand combat to make use of) and magic spells, she's another prominent female protagonist with plenty of personality (which what makes this important is that Samus is still the only character that qualifies as one on the roster... and even Zero Suit Samus is actually an iteration of Samus that's only had a meaningful playable role in one game, Zero Mission, and even that wasn't much), she can work as the primary "indie" rep as Nintendo has wanted to work with indie developers for some time, the Shantae franchise's main presence has been on Nintendo's systems (and is planned for localization in Japan in the future; that said, the games are available on PC there), and she has the perfect setup for any number of movesets. If they decide to give certain DLC characters stages and Ryu wasn't just a very special case, there are plenty of choices for that as well along with music from the Shantae series.
Her inclusion wouldn't just be a major bone to throw to her fan following and WayForward; it would also mean more people being exposed to the series which is easily available on PC or the eShop for them to try out. And there's the fact that her next game, Half-Genie Hero, is coming out this year (at the earliest), a Wii U port included. And on that note, Shantae and the Pirate's Curse has repeatedly been one of the eShop's best-sellers.
I'm putting indie in quotes because of how WayForward's, and the franchise's, status as indie is disputable. Technically, all "indie" means is something developed and published by an independent studio. It doesn't automatically mean low-budget or obscure. I'm saying this because it's a label that tends to be viewed in a negative light. However, whether or not they're indie, it's worth noting that WayForward being a smaller developer (and especially one with a good history and relationship with Nintendo) would mean few problems with licensing the IP compared to major third-party additions.
(I will admit however; one influential factor in making me decide to support her is that she's a character suggestion that hipsters around the internet get pissed off over; it would make my day if the people believing she has no fanbase and are afraid of her "taking" their own character's spot were all shown up by this actually happening)