So, LeakerBros. I'm going to assume his leak is separate from Sal Romano's in order to eliminate the potential 59 character roster and gives his leak a bit more realism. I'll be basing these points on just what LeakerBros has said.
Rant:
/spoiler-Ness, Lucas, ROB, Wolf, Falco, and Ganondorf(Major overhaul) are returning veterans. This seems very believable, and I expect this to be true.
-Shulk, Hades, Ridley, Chibi Robo, Mike Jones, Takamaru, Avatar and Bandana Dee are Newcomers.
-Shulk is probably in, very popular choice on both sides of the globe, the game was a big success and very positively reviewed, and he is the only character shared between this and Sal's leak. I believe this.
-Ridley is inevitable at this point. If Sakurai teased the fanbase this hard to just make him a Stage Hazard/Boss, then that is just plain cruel.
-Takamaru is also more or less a shoo-in. The most popular retro choice remaining by far, plenty of recent cameos, and would further extenuate the East/West theme (Little Mac/Takamaru, Mike Jones/Lucas).
-Avatar would be a better choice than Chrom in my eyes. Fire Emblem is getting an Awakening rep in some form, and Avatar would be more in the way of customization, as well as uniqueness. I can see this happening as well.
-Chibi Robo is the little robot that just might make the cut. He was recently rebooted on 3DS with the photo finder app, as well as representing a new series, with a very good potential for a unique moveset. I can buy this as well.
-Hades is a toss up. In my eyes his chances as a playable character depend completely on the existence of Palutena as a playable character before him. Even then he is in a toss up with Medusa for that spot. 50/50 here.
-Bandanna Dee. I don't know enough about Bandanna Dee to comment, but if Kirby were to get a fourth rep, Bandanna Dee would be that rep, and with Sakurai's pandering to his own series, this could happen.
-Mike Jones is hard to believe. This can only be true if his previous statement about StarTropics being rebooted is true. If that is true, then I can indeed believe that this could potentially happen.
-F-Zero and Starfox not getting newcomers is very believable. Samurai Goroh is an Assist again, and Black Shadow would probably only happen if Ganon was overhauled, and in this leak, I assume that Ganon's old moveset more or less goes to Hades. Starfox is lucky to have three reps at this point, and Krystal only happens if one of the others is cut, which he claims they are not.
-DK and Zelda get newcomers. This is very believable as well. No arguments here. If Mario and Pokemon get new characters, I would assume that Zelda would as well. DK is long overdue for its third character./spoiler
TL:DR This leak seems a little out there, and probably isn't true. However, if you stick within the bounds of the leak, don't combine it with Sal Romano's, and assuming everything the leaker says is true about other games' development, then the leak doesn't seem so far-fetched to me and could actually be true. Yes, some of the choices are far-fetched, but if they tie into Sakurai's pandering of his own series, and the devleopment of the games he claims to exist, then the leak makes a surprising amount of sense.
Also: I hate to ask, but how do I put this thing in spoiler tags as to not clutter the whole page.