That was my same problem too I followed the list thought I did everything right. Then I looked through all the titles saw I was missing a title with someone (forgot who probably was Zack too). Then got it through doing arcade.
Survival is about finding a good combo that the computer will hardly counter. That's what I did with Tina and got through legendary. There's other things that play a factor of course. That's how I got through with it with so many characters.