I'd be surprised if no one has pointed this out yet but I just realized the trailer says "6 all-new DLC characters", which IIRC is exactly what the SFV Akuma trailer said at the end. It's probably a pretty safe bet that none of them have been in a Marvel vs. Capcom game before.
Original Characters Confirmed.
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Seriously though, this is pretty awesome. New to the series Marvel and Capcom characters. Each reveal will be exciting.