Last part is kind of confusing. Was your friend hinting that he knew of a couple new characters that weren't shown off at E3 exclusively, or was he referring to the roster as a whole? If its just E3 I can imagine Little Mac, Mii and Pac-Man being the characters shelved for a later date; just hoping what I'm reading into your words isn't what I think it means.
They didn't say E3 exclusively, I think the term they used was "in the trailer", so I interpolated E3 into the quotation with the square brackets []. I assumed by "the trailer" that they meant "the E3 trailer".
Sorry, I don't know if that clears up anything. I'm not sure what you're asking exactly.
One other thing they said was that MK8 is amazing and that the online is fantastic. I don't think that's news though lol.