Can someone fill me in on the "Power of Six" Theory?
The Power of Six theory was proposed by
JudgeHeihachi
on GameFAQs.
https://gamefaqs.gamespot.com/boards/234547-super-smash-bros-ultimate/78143628
The theory posits that each fighter was originally supposed to come with 6 Mii Fighter costumes/hats each, and in the process would bring back every third party costume from Smash 4 that was missing from base Ultimate. The way it would've initially worked out is as follows:
Joker: 4 Persona costumes, Tails and Knuckles costumes from Smash 4.
Hero: 4 Dragon Quest costumes, Geno costume and Chocobo hat from Smash 4.
Banjo: Proto Man, Mega Man X, Zero, Mega Man.EXE, Hunter Armor and Rathalos Armor from Smash 4.
Terry: 3 King of Fighters costumes, Jacky, Akira and Heihachi from Smash 4.
FP5 (persumed in the post to be Ryu Hayabusa): 4 new costumes, Lloyd and Gil costumes from Smash 4.
According to this theory, the initial plan was that the 5 Fighters Pass characters (and Plant) were all we were getting for DLC for Ultimate, but because of how stupidly well the pass sold, more DLC Fighters were decided upon almost immediately after it went up for preorder and things got a bit shifted around to accommodate. This explains why every Fighters Pass character after Joker has come with less than 6 costumes: Those costumes, more specifically the IPs, are being held back for later use in next year's DLC either as costumes to come alongside these new fighters, or as fighters themselves.
The characters/costumes currently unaccounted for are as follows: Geno, Chocobo, Mega Man X, Mega Man.EXE, Hunter Armor, Rathalos Armor, Heihachi, Lloyd and Gil. Geno is speculated to have been held back to be included as a fighter, with the Chocobo hat to return alongside him. This would also line up with the Mii Fighter list and CacoMallow posts, which detail a Mallow hat coming to the game but no Geno costume. The 4 Capcom costumes are speculated to come with a new Capcom character, either Phoenix Wright, Amaterasu, Dante, or any other Capcom character that would fit the bill.
Alternatively, the Mega Man costumes could come with a fighter that specializes in guns with the Monster Hunter costumes coming with a sword fighter, akin to how the Akira and Jacky costumes returned with Terry who specializes in up-close brawling. That gun-based fighter could potentially be Doomguy if the CacoMallow post is legit and the Cacodemon hat is indeed coming to the game. Heihachi/Lloyd and Gil are speculated to come alongside a Bandai Namco character, with either Lloyd or Heihachi being upgraded to fighter status, with most people gravitating towards Lloyd. This would work out well if we were to have fighters that come with costumes related to their fighting style, with Lloyd being the sword fighter.
So that's Power of Six theory. Right now we have no idea who FP5 is, so it's possible that this may not pan out this way, but it's really interesting to think about. Speaking of, writing out this explaination has given me an interesting idea as to how this could all play out:
Geno as fighter: Mallow Hat, Smithy Costume (Swordfighter), Chocobo Hat, Tifa Costume (Brawler), Sephiroth Costume (Swordfighter), Crono Costume (Swordfighter)
Doomguy as fighter: Cacodemon Hat, Revenant Costume (Gunner), Vault Boy Costume (Brawler), Dovakin Costume (Swordfighter, comes with Skyrim theme a la Sans), Mega Man X, Mega Man.EXE
Lloyd as fighter: Yuri Lowell (Swordfighter), Luke fon Fabre (Swordfighter), Tear Grants (Swordfighter), Dig-Dug (Gunner), Heihachi, Gil
EDIT: Sorry if this isn't on-topic enough Mods, but I started writing this post before you warned people and by gum and I gonna finish it!