Well other people are doing it and caving into peer pressure is cool right? Here's my "if the leak is true" prediction roster. More characters than I usually guess at, around 75 i think mattering to how you count miis, i usually go for 65-70 but part of this leak is that there are no cuts and they are going for the "ultimate" smash roster.
That said, I brought everyone back except pichu and young link as I think all the veterans scored high on the ballot and would have to be part of the "ultimate" end all roster. Squirtle and Ivysaur are back along with Eevee. yeah that a lot of pokemon reps, but if we are going back to kanto with a yellow remake satring pikachu/eevee I think this actually makes sense all things considered and two are just returning vets, much easier on the design team. I do think eevee has an amazing evolutions mechanic potential and i also think gamefreaks would have pushed sakurai to use him so i think it fits, again if the leaks are true. If simon is happening I expect Snake is returning and again with an ultimate roster and konami being involved AND the smash ballot... my guess is if the leaks true hes back along with most of the other cut veterans and going to konami was initially to GET snake back to satisfy the fans (as veterans seemed to universally score higher than anyone else on the ballot from the numbers ive seen people tally). Ice Climbers of course returns with the leak but again if we are bringing everyone back Wolfs back too once again due to the ballot and making the "ultimate" roster.
A lot of long time fan requested characters show up here, if ridleys in and we are going for pleasing the fans than dixie, k rool, waluigi, toad, waddle dee, simon, and geno are all highly requested characters and have been for a long time. Maybe im being biased with geno but i really think his time is now and that newcomer splash image his mii costume got... it just seems too fitting if everyones returning we still have square and cloud and if the ballot and the mii costumes were more of a tease for this next game, characters like geno and k rool and of course inkling all feel highly likely here and should be part of that ultimate fan roster. i dont think its absurd for DK to get two reps and dixie and k rool both seem highly requested and worthy. waluigi upgraded from an assist trophy and even when he was revealed as an assist trophy sakurai seemed to hint at "playability" and him not quite making the cut, with mario aces around this time it just feels right to have him in reping the sports games.
some of the odder choices, sakurai always throws curve balls with wtf reps and retro reps etc... I got chorus kids here for two reasons 1. they were already worked on for smash 4, this we know, and im guessing it was the same reason ice climbers were cut they didn't make it so heres the opportunity for that rhythm heaven rep (chorus kids or someone else) we know sakurai meant to add and 2. they got found out about and thus when it came time for the ballot they had fans, so sakurai might feel obligated to give us what he tried to give us in smash 4. Then theres takamaru, i just honestly just cant think of a better retro rep, a samurai is unique seems like the type of series sakurai would want to "revive" and its actively gotten more attention in the last few years than ever before. balloon fighter/excite biker are possible along with a few others (i like the hanafuda and labo idea but im wary of "guessing" at either for various reasons).
for really new reps we already got inkling but i also put in rex/pyra, i just have them both as some form of character as i dont know much about xenoblade but what i do know is sakurai said something about liking the new game, we have the series already established so a very new character may have been chosen while both games were still in development (unlike say, ARMS where i feel sakurai will "wait" to see the series staying power and it was too early to choose a brand new IP for a character spot).
Zelda i didnt add new reps for but i do think link and probably zelda will get overhauled with BOTW stuff so that might be enough to feel as though the series got attention. probably classic link/zelda alt costumes and maybe an impa alt costume for sheik? same with keeping alph and probly adding a toadette alt for captain toad, heck add daisy or anyone else who they could make work that way, i think alt costumes will be big this time honestly.
nothing new for FE i think after getting complaints of "too many reps" and no cuts this time plus corrin getting in at the end of the DLC, FE can sit tight right how it is and feel ok in this new roster that balances out a few series (metroid,dk) without any new reps for fire emblem. same for kid icarus, earthbound etc... i just think these series are where they should be. Animal crossing could certainly get a new rep but somehow i feel sakurai barely warmed up to the idea of villager so i think he'll see that as enough of a fighter rep and characters like isabelle and nook are better suited to assists and stages etc... thats just how i think sakurai sees the series not my personal feelings.
So thats my prediction as of right now with the leak, im open to criticism as i just took the leak and followed where it could go logically step by step. Also this would be the BASE roster which would be nuts considering DLC is basically a given, so theres a few other characters like rayman i think are highly likely but i found tough to find space for but still think they'd make it in by the end of it all. Also speaking of Rayman, i think its likely more third party characters could be added from companies like namco getting more reps or even an indy rep (shovel knight) but its just so tough to guess at those and i think like last time many might be saved for DLC as they tend to be pretty hype and will get people paying for em.