Why Miis?
Before I start analyzing things, I think it's important to get this bit out. Why should Miis be in Smash?
Well, for starters, Miis are near omnipresent nowadays. Ever since their introduction as avatars on the Wii, they've had recurring roles in numerous Nintendo games, to the point where it's difficult to keep track of them all. Aside from just games, Miis have become an icon for Nintendo as of late, with their prominence on the Wii being expanded upon on the 3DS (which is notable, considering that the 3DS has nothing to do with the Wii and didn't need to incorporate Miis, especially since there's no pun to be made) and the Wii U, the latter of which they are particularly prominent in through Miiverse, a new feature introduced that allows players to discuss games using their Miis. There's simply no denying the prominence Miis have now. So, when you have a game like Smash, a game that is known for bringing together Nintendo All-Stars together into one title, Miis seem like a good choice for being playable, as at this point they could certainly be considered Nintendo All-Stars. Of course, being an icon for Nintendo alone is not enough; characters also have to be capable of fighting it out with the other All-Stars on the roster. In other words, they need to have a move set to use. Fortunately for Miis, the numerous titles they've appeared in give them plenty of material to make a coherent move set out of, ranging from the sporting equipment from Wii Sports to magic and swordplay from Find Mii. Overall, Miis have a lot of good characteristics that would make them perfectly reasonable additions to the Smash roster.
Yeah, just wanted to get that part out of the way early. I do legitimately think that Miis are a justified addition to the Smash roster. Now obviously there is a ton of controversy regarding Miis being in Smash, with a lot of people hating the very concept of Miis being playable, and others who think that Miis would be too much of a technical challenge. Now, personally, I don't believe that either of these things would keep them out of Smash. Just as there are a lot of people who dislike Miis, there are a number of people who like them, and would enjoy seeing them in Smash (the existence of this thread is proof enough of that). And considering how Miis have been implemented into numerous other games at this point with no apparent difficulty, and considering how there are already very complex characters in Smash, a little bit of technical issues probably wouldn't stop Sakurai. So, the bottom line of all this is that Miis are justified, reasonable inclusions in Smash, and the reasons against their inclusion, while not beneficial to their chances, do in no way rule them out.
However, the main focus of this analysis isn't why Miis should be playable, or anything like that. The focus of this is to analyze what evidence we've actually seen in Smash 4 that supports or goes against the idea that Miis are playable in Smash.
Supporting Evidence
+ A stage based on Pilot Wings is present in the Wii U version of the game. This is notable due to the fact that the stage prominently features Wuhu Island, the setting for multiple "Wii" titles that heavily feature Miis. Miis have not been seen on the island thus far.
+ A stage based on Find Mii is present in the 3DS version of the game. As Find Mii is a game that's entirely based on Miis (compared to the Pilot Wings stage, which comes from a series that existed long before Miis), this is an ideal home stage for the Miis if they are playable.
+ A stage based on Tomodachi Life is present in the 3DS version of the game. Tomodachi Life is another game that focuses on Miis, in this case using them as citizens in a life-simulation game. Like the other stages before it, the presence of this stage in the game may hint at the appearance of playable Miis.
Well, I believe that's everything. If I left something out, do let me know. Now then...
Damaging Evidence
- The Pilot Wings stage, despite featuring Wuhu Island, may not mean much for the Miis being playable, as the Pilot Wings series has existed long before Miis have, and may simply be referencing the latest installment in the series as well as the older ones.
- The Miis appear as icons for players in Online mode, representing players and their "Global Smash Power." While not a de-confirmation by any means, this is an instance of Miis appearing in Smash in a role other than that of a playable character.
- One of the Miis biggest titles is Wii Sports, which many fans thought would be an ideal source to pull material from to make a move set for the Miis. However, another character on the roster, the Villager, already uses items like a bowling ball and boxing gloves in his own move set. Now, again, this obviously doesn't de-confirm Miis, as Little Mac was revealed sometime after the Villager, despite both utilizing boxing gloves for their move sets. However, it is something worth noting, especially considering that both the Villager and Miis are avatar characters who (would) use random props and items from their games to make a move set out of.
- A Mii appears in the cage of the Find Mii stage. As Toon Link has shown us, characters who appear in the background of stages are not necessarily de-confirmed. However, like with the Miis appearing in Online mode, this is an instance of Miis appearing in a role other than that of a playable character. While it's far from a de-confirmation, it is a strike against them.
- The Find Mii stage has a Find Mii crown for its series symbol (here we go...). This is a small but rather interesting detail that could mean a lot for the Miis chances. Within Smash, series that have representation through characters or stages are given a symbol to identify themselves with. The symbol for a series is usually something generic that can encompass whatever series it stands for as a whole (for example, the Mario series is represented by a mushroom symbol). The symbol of a series is then applied to any characters or stages that originate from that series. The Find Mii stage's symbol is rather interesting because of this. The stage is represented by a crown, which is clearly based on the crown worn by the King Mii that you work towards saving within Find Mii. In terms of representing Find Mii as a series, this fits in perfectly with the previous examples of symbols we've seen. However, if Miis were to be included as playable characters, the Find Mii stage would be an obvious choice for a home stage, as it comes from a game focused entirely on Miis. Given how closely the Miis and Find Mii are tied together, it would make sense that the stage would share a symbol with the Miis if they were playable. However, the crown symbol makes little to no sense as a symbol for the Miis. For one, the crown is distinctly based on Find Mii. If the Miis used this symbol, it would tie them to that specific game and that one alone, despite them appearing in numerous other titles aside from that (like Tomodachi Life, which is also getting a stage). Also, it is highly unlikely that the Find Mii stage will appear on the Wii U version of the game; thus, the symbol used by the Miis would have no meaning on that version of the game. Now, it could be argued that the Miis have no real series, and that the stages based on the Miis games could have their own symbol while the Miis have one of their own. However, this still doesn't make much sense. Despite not being part of the same series, the games based on Miis are still based on Miis. The games are all connected by the appearance of the Miis, thus making them "Mii" games. This is, in a way, similar to the Mario games. Games like Mario Kart, Luigi's Mansion, and Paper Mario aren't really part of the same series as, say, Super Mario Galaxy, being completely different genres and having multiple titles within that genre. Yet those games are still Mario games due to the presence of Mario characters and themes. Similarly, this translates into Smash, where stages based on Mario Kart and Luigi's Mansion share the same mushroom symbol that the rest of the Mario stages and characters do. Going off of that, it makes very little sense for the Find Mii stage to have a different symbol than that of the Miis if they are playable, considering that, even if it is distinct from other "Mii" games, Find Mii is still a "Mii" game. The most logical explanation for why the stage has a symbol different from that of the Miis is quite simple; Miis are not playable, and thus there is nothing to tie the "Mii" stages together, and each stage simply represents its own small series.
Well, I think that about sums it up. So, basically, what the Miis have going for them at this point are some stages based on games that Miis have featured prominently in. What they have going against them is them appearing in Smash in ways that aren't as playable characters, possible move set options being implemented in other characters, and the stages based on the "Mii" games possibly not associating themselves with any playable character.
In my mind, the negatives outweigh the positives. I find the Miis unlikely at this point.