You know, I've noticed something about the way these last two DLC characters have leaked.
As we know, Tansut had a source from most likely within Square-Enix that told him Cloud was coming to Smash 4. Years later, that same source came and informed him that a Dragon Quest rep of some kind was coming. Tansut asked if it was Erdrick and wasn't denied, obviously because Erdrick would end up being included as an alt.
With Banjo, there were quite a handful of people tight with Microsoft that were saying he was in, way before Shinobi. Like I posted before, Indie Gamer Chick, who does seem to have actual connections to MS,
made several hints at upcoming collaborations between Nintendo, Microsoft and Rare, including teases at Smash DLC. Shortly after the VGAs last year, an Xbox enthusiast by the name of Rand Al Thor mentioned that his sources at Microsoft told him that Banjo was coming.
36:45
We also had the Windows Central fiasco back in March, where Sabi was informed by the editor there that his MS sources, too, told her that Banjo was coming. Then lastly Shinobi, who's been known to have inside info regarding Xbox/PS4 stuff, came out with his cryptic tease last week that changed everything.
So yeah, it seems like everyone close to Microsoft was told that Banjo was happening. So I guess the moral of the story here is, between this and Tansut, the best way to leak a third party character coming to Smash is to have a source within said third party lol