You can also ask your question on our X-Men: Children of the Atom Questions & Answers page.
At the 'Character' select screen highlight Spiral and wait a couple of seconds before pressing Left until Iceman is highlighted. Then wait another couple of seconds and press Right, Up, Right, Right, Down to highlight Silver Samurai. Wait a couple of more seconds and then press HP + LK + HK.
As soon as you've won a match press 'Start' quickly to continue hitting the defeated character.