It would be refreshing to see Pyro creating some firey animals to attack the X-Men during the final battle (dragons, lions, phoenix birds, snakes, etc.).
As for Iceman, it would also be cool if he did a throwback to X2 and create an ice wall/shield to block Pyros flame attacks. I can see Pyro taunting Iceman on how weak he is (by shooting intense flames at him), and that he's not pushing his powers as hard as Pyro is. Then, when it gets too hot for Iceman to handle, Pyro's feet and legs begin to freeze up, and he is slowly encased in ice. Iceman then ices up, and whispers a one liner to Pyro, and joins the rest of the battle by taking off on an ice slide... Leaving Pyro frozen and immobile.