Chun Li, Cammy & Rose from Street Fighter
Since I suggested Bison in the villains thread, it seems apropos Diana would be allies with some of the ladies of
Street Fighter. Chun Li is an Interpol agent determined to take Shadaloo and Bison down. Cammy was one of Bison's Dolls (and back-up vessel in case he died) until she lost her memory. She now works with British Special Forces and is also determined to destroy Shadaloo, free the other Dolls, and redeem herself for the things she did serving Bison. Finally, there's Rose, who is a fortune-teller and sort of Bison's good counterpart who works to destroy him once and for all. I think she'd get along with Chun Li, be very supportive of Cammy, and Rose...who tends to be a little suicidal with her efforts to defeat Bison...she would try to guide her to a better path.
Kitana from Mortal Kombat
And since I also suggested Shao Kahn, it would make sense for Diana to align with Kitana against. Technically, they did meet in
MK vs. DC--and were set up as their respective universes' counterparts--but the story didn't do anything interesting with Diana and wrote Kitana like garbage, so we'll ignore that. Anyway, Kitana was Kahn's adopted daughter and served as one of his assassins for most of her life until she learned the truth about her real parents. She's since dedicated herself to overthrowing him and restoring her home, and she'd be a natural ally for Wonder Woman. I think Diana would respect Kitana for her perseverance and drive to set things right, and lord knows Kitana needs all the support she can get 'cause her life sucks.