Latest characters announced:
Haggar of Final Fight fame for Capcom
Phoenix for Marvel. If Phoenix is the last character standing and has 5 full life meters, if she is KO'd, she revives as Dark Phoenix with a full life meter that gradually depletes. Giving her until her life runs out to eke out a victory against her opponent(s).
Also announced:
Akuma for Capcom, of Street Fighter fame (also my avatar)
and Taskmaster for Marvel.
Niitsuma, head producer has announced that only 2 characters are left to be announced and there is also a possibility of more being added via DLC.