I have gotten all the secret characters besides Dark Pheonix and Pyro, when i look in the game assets section in the game it said i had to get the second ending of story mode. When the last battle comes you get to face Bastion with Magneto once, then if you lose, an infinite amount of times with Pheonix. I thought by beating it with Magneto I'd get the second ending ( With Dark Pheonix ) but i didn't get her so i went online and everyone says you have to beat arcade with Pheonix to get Dark Pheonix. I tried that, AND the code that gives you all characters and costumes but nothing has worked! Could somebody please help me out?

you have to beat bastion with Phoenix and get a perfect or you can enter a code