I once came across a 4chan post from a person claiming they were PMBR and were pissed off about something, so they spilled some spoilers. Said sometime after EVO2013, there would be a pretty big announcement. He claimed the clone engine was practically completed and Roy and Mewtwo were already being developed. Others he confirmed are Lyn, along with some cool details about her moveset. Fire arrow for B, DownB counter, she's really nimble and has an OHC system like Lucario. He also said they were using a female character's voices from Dynasty Warriors for Lyn's voice effects. (Actually, this would make a lot of sense considering it was now also recently made possible to hack custom sounds without Riivolution.)
The leak also claimed Isaac from Golden Sun would be added, and then said that those were the only 4 characters that were for sure in. Other characters that were apparently on the table were Trixie Kong (this character should've been Smash a long time ago. Please, ranged hair grab?), Waluigi, Sammie from Advance Wars (who the ****?) and uhhh there was one more. Oh, Knuckles, and said a few things about ideas being tossed around for his moveset. Glide, dig, wall climbing (I hate him already.)
This may not be true anyways. Though, when I inquired about this rumor to a BR member I know, he said "I wouldn't pay attention to rumors." Which I normally don't anyways but this one felt realistic. But then Roy was just spoiled, so I imagine he was just shaking me off, no hard feelings.
WHO KNOWS. I've been sitting on this for months now, it sounds more credible to me as time goes on but I'm not wasting my time investigating it. Take what you will from it.