Also, I've been doing some... uh... "roster math", like Shadow Math, but smarter.
[collapse="First, compare the Melee starting roster to the Melee final roster"]
The top and middle rows go from 7 character icon slots long to 9 character icon slots long, while the bottom row goes from 5 question mark box slots long to 7 characters icon slots long.
That's a 2 character icon slot growth per row, or 6 character icons total for 6 "unexpected" characters.
Some say this could be the clone case, but I think my next point my prove this potentially wrong...[/collapse]
[collapse="Now look at the starting Brawl roster vs. the Brawl final roster."]
The top 2 rows start out 8 character icon slots long each to 9 character icon slots long each. The 3rd row (the bottom row on the top picture) goes from 6 character icon slots (including the random) to 9.
Meanwhile the 4th row wasn't even in the Brawl starting roster, but it grows out to be 9 character icon slots as well.
So literally, we gained 2 icon slots total from the top 2 rows, 3 character icon slots from the 3rd row, and all 9 character icon slots on the bottom row.[/collapse]
That means the roster went from 24 character icon slots to 36 character icons slots, or 50%.
With Melee it grew 32% roughly, counting the 5 question mark boxes. If you take out the 5 question mark boxes, it grew roughly 79%.
If we did that approximately numbers, if we applied that growth from 37 icons in Smash 4 (the starting amount of Smash 3DS' roster is 1 greater than it is in Brawl; the 37 icons are all the starters [obviously with no transformations] minus the Mii Fighters plus the random icon box), it would be:
-For the 32% in Melee (the smallest growth) counting the question mark boxes it would be 48.84 icons. That rounds out to 47 characters, excluding the 3 Mii Fighters, or 50 characters total (round either way, hopefully up). That's less than what is already confirmed, so that's debunked, lol!!!
-For the 79% in Melee (the largest growth) not counting the question mark boxes it would be 66.23 icons. That is 65.23 characters, excluding the 3 Mii Fighters, or 68.23 characters total (round either way, hopefully up, although a GIGANTIC amount, lol!!!).
-For the 50% growth in Brawl (the middle growth) it would be 55.5 icons. That is 54.5 characters, excluded the 3 Mii Fighters, or 57.5 characters total (round that up either way, hopefully up).
Either way between those last two (because the first one is dead) that ranges from "WOW THAT'S A LOT" to "HOLY CRAP I'M DROOLING AND I CAN'T STOP!!! I JUST FLOODED MY ENTIRE CITY AND I DON'T EVEN CARE!!!!"
But I'm going to assume that math is not as relevant as the row stuff. I will now craft a theory based off just the minimalist 1 vertical column opening up (because I assume some characters, specifically the Chorus Kids/Men and the Ice Climbers, will be held off until Smash WiiU), which would give us a max of 60 character icons, or 59 characters total.
Either way, given how the roster in Melee moves (Luigi is one of those question mark boxes and moves to the top row once Dr. Mario is unlocked), I think it's safe to say that Dr. Mario, Lucina, and Dark Pit will likewise do the same thing.
With with all that said, here's the starting roster for Smash 4:
As it stands, we have 6 rows. the top 4 rows all have 8 characters, while row has 5 characters plus the random icon.
There are 36 characters, or 37 total icons.
Now let's look how it works when all the confirmed characters are unlocked...
So here is what happened:
The top 4 horizontal row grew by 1, and now have 9 characters. The 5th row grew by 3, and the 6th row was added, and it grew in 4 characters and 1 random button, or 5 slots total.
In terms of characters, however, things changed.
-In Row 1, the unlocking of Bowser Jr. and Wario bump down DK and Diddy. This obviously infers there are more Donkey Kong franchise playable characters.
-In Row 2, obviously DK and Diddy have slid down a row. Next, Pit and Palutena went down a row. Additionally, Little Mac went up a row. It is obvious that this is because Dark Pit will be added when the rows expands, which also infers the rows expand a second time (just like in Melee).
-In Row 3, obviously Pit and Palutena moved down (and Dark Pit will be there when the row expands). We got the 3 Fire Emblem characters, and obviously Lucina will go up with the row expands. Rounding it out are the 3 Kirby characters and Little Mac. Obviously when Lucina and Dark Pit go up and the rows expand, Little Mac goes down a row. Fox additionally got slid down as more characters were unlocked, again, inferring Dark Pit and Lucina if we didn't already know they were playable.
-In Row 4, Fox came down based on the previous row evidence, while Falco was unlocked. The Pokémon slide over, and Jigglypuff was unlocked. Captain Falcon, the Villager, The Wii Fit Trainer, and Olimar all go down a row. The Duck Hunt Dog and ROB were unlocked.
-In Row 5, Ness, Captain Falcon, Villager, The Wii Fit Trainer, and Olimar moved down. Dr. Mario, Dark Pit, and Lucina were unlocked and added. Shulk, Pac-Man, Mega Man, Sonic, and the Random Icon all moved down.
-Row 6 was added. The previous Row 5 became Row 6.
(excuse the side icons; those are alt outfits)
I think the biggest reason the roster will grow horizontally by one icon per row is because of how the Donkey Kong characters moved down, and why the Kid Icarus and Fire Emblem characters are set where they are.
I theorize that:
1. The horizontal rows will increase to 10. I say this because Dr. Mario will "go up" to the top row like Luigi did in Melee, or how Diddy went from row 1 to row 2 in Brawl.
2. This means that the top 5 rows will have 10 characters.
3. Lucina and Dark Pit will go up with their franchises.
4. The bottom (6th) row will have at least one more character. I don't think it will be the Chorus Kids or the Ice Climbers (I think they'll be DLC or on Smash WiiU)
So if we go by this, the logic is set:
Row 1:
The top row is as is, except Dr. Mario is up there. He's either to the left or right of Wario, but definitely to the right of G&W.
Row 2: The second row would have The Metroid franchise characters move down, as Ridley is almost a for sure thing. That clears up two spots. Seeing as how the only characters on this row are Donkey Kong, Zelda, and Little Mac from Punch-Out!!, I think we can agree one of the following presumptions are.
-1: At least 1 of the 2 new characters on this row are Donkey Kong newcomers (either K. Rool or Dixie). We are
GUARANTEED either K. Rool or Dixie.
-2: Potentially both of these 2 characters on this row are Donkey Kong newcomers (so K. Rool AND Dixie).
-3: Zelda could get one newcomer (likely Impa with a super outside chance of Toon Zelda or Tetra), however, this is up in the air.
-4: We could get a confirmed character moving up (namely Little Mac), but this is STRONGLY doubtful.
-5: Samus and Zero Suit Samus are CLEARLY moving down a row.
-6: Little Mac is clearly moving up, either in between the Donkey Kong and Zelda characters (because the 1st Punch-Out!! game came out before the 1st Zelda game), or at the very end of the roster.
Row 3:
1. Since Samus and Zero Suit move down, that clearly de facto confirms Ridley.
2. With Pit and Palutena moved down, Dark Pit is clearly going to be added.
3. Lucina will move up.
4. With Samus and Zero Suit Samus moved down, Ridley, Dark Pit, and Lucina added, and Little Mac moved up, let's do the math. 2 + 3 = 5. 5 - 1 = 4. That's 4 more characters.
5. With that logic, and how we are gaining one roster slot horizontally, that means we are 3 characters over. That means Kirby, Dedede, and Meta Knight all will move down to Row 4.
Row 4:
1. Kirby, Dedede, and Meta Knight all are now moved down a Row.
2. Fox, Falco, Duck Hunt Dog, and R.O.B. all remain on the row.
3. All the Pokémon move down a row.
4. This means we got 7 characters out of 10 left. We can theorize who this is.
-1: IMO I think Wolf is going to be late game unlockable character, just like he was in Brawl. I wouldn't call him a lock, but I say there is a distinct possibility of it. So that's 8.
-2: If Lucas is in, Ness and Lucas will move up to this row, making it 10.
-3: Even if Lucas isn't in, Ness may still move up.
-4: We might get a retro character instead of Lucas. I think it would almost definitely be Mach Rider, but Sukapon is also a distinct possibility. The Excite Biker, Andy, The Balloon Fighter, Chibi-Robo, and Ray MK could additionally happen, although those are long shots.
Row 5:
1. There's plenty of room for Mewtwo, because that's happening. That's 6 characters right there.
2. Captain Falcon and Ness will either be on this Row or Row 4.
3. Villager, Olimar, and The Wii Fit Trainer will either remain on this row or move down to Row 6.
4. Lots of newer characters (like 1998-on) could go in this row or the next row.
Row 6:
1. Shulk, Pac-Man, Mega Man, Sonic, and the Random icon will stay there, but we're at least getting another character.
All of this I think is "proof" that based on just even the roster layout there is a AT WORST 75% chance K. Rool is playable.
AT WORST!!!
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Here is one of 2 finalized version of a mock roster I made. I have 1 more finalized, and 3 that I am working on finalizing (note: I stuck with the minimalist amount)