Starting Roster Predictions!
These are my thoughts so far, and I'll be going in order of Smash games.
Starter Predictions from Super Smash Bros 64.
Mario
Donkey Kong
Link
Pikachu
Kirby
Fox
Yoshi
Samus
(The original 8! I don't think they'll ever change.
) Luigi
(This is my opinion, but seeing as how we've known that Luigi has been in the game since the beginning, I think maybe this time he'll be a starter. These are just my thoughts) (9 Characters)
Starter Predictions from Super Smash Bros Melee
Bowser
Peach
Zelda
Sheik
Marth
(I think that since Fire Emblem has become a more prominent franchise, it might make more sense for the mascot to be playable from the beginning.) Ice Climbers
(I know we haven't seen them yet, but I don't think they'll ever be cut.) (5 Characters)
Starter Predictions from Super Smash Bros Brawl
Charizard
(Perhaps it'll carry the Pokémon Trainer's starter status too.) Ike
(Given that Ike was a starter last time, I think maybe he'll be a starter again.) Pikmin & Olimar.
Sonic the Hedgehog
(I think that unlike most third-party characters, he's been here the longest in Smash, so I think this time he might be a starter. I could be wrong!) King Dedede
(Quite obvious from being a Kirby character, not to mention he's just as important to the series as Kirby) Pit
Zero Suit Samus
Diddy Kong
Lucario
(We don't know just yet. Maybe) (9 Characters)
Newcomers for Super Smash Bros for Nintendo 3DS and Wii U
Wii Fit Trainer
Villager
Little Mac
Palutena
Mii Fighters
(I think these two will be starters so that players will get used to customising their character right away.) 5 Characters.
With that in mind, I imagine that the starting roster should be around...28 Characters. I could be wrong, but these are predictions.