4. Colossus Vs. Juggernaut
It almost defies belief that an X-Men film with Colossus and Juggernaut in it would not have them fighting one another. In the comics, Colossus and Juggernaut are fierce rivals and are often testing their strength against each other. I can imagine an epic battle between Colossus and Juggernaut, with each trading massive blows, cracking the ground and buildings around them. At the young age Colossus is shown in the film, it is unlikely that he would be strong enough to defeat Juggernaut by himself. Maybe Kitty could help Colossus defeat him by using her brains to outsmart Juggernaut. The battle could also have been used to show the beginnings of a Colossus/Kitty Pryde relationship, with Kitty being suitably impressed by Colossus' courage and strength in taking on Juggernaut.