We have Ryce's leak of 28 characters, msot have been revealed so far.
http://www.neogaf.com/forum/showpost.php?p=238619370&postcount=11743
Then we have something about the story that's a tad fishy, but it's still plausible. https://www.reddit.com/r/mvci/comments/6ggqlm/marvel_vs_capcom_infinite_story_information_dlc/?sort=new
And finally, a few days prior to E3, a set of images popped up on reddit and were deleted. These showed files for charcaters that appeared in the E3 story trailer, along with characers not seen/not in Ryce's leak https://www.reddit.com/r/mvci/comments/6f9t4a/images/
image:
https://pbs.twimg.com/media/DCPlCgVXYAAWB98.jpg
>>380683834
Fuck