For Tifa fans out there, here are more additional information regarding Tifa's appearance in Dissidia 012. As we all know, her appearance was confirmed in the last scene on the extended Dissidia 012 trailer.
It is confirmed via her Twitter account that her VA in the English version, Rachael Leigh Cook, who did her voice in Final Fantasy VII: Advent Children will reprise her role in the upcoming game. Aside from that, we have a glimpse on her gameplay in the latest scan (See left.)
Her EX Mode is Equipped Premium Heart, which allows her to equip her strongest weapon in FFVII. Aside from that, her EX Burst allows her to use her infamous slot machine type Limit Break! Yes, those Hit!, Yeah! and Miss! boxes will appear in Duodecim.
And like you have all guessed, Tifa's alternate costume, just like Cloud in the previous game, is the costume she wore in Final Fantasy VII: Advent Children.
Source: Final Fantasy Wikia, XenonVincent777 - Scan