Shadowcat
Kitty Pryde, Ariel, Sprite, she has had a lot of names in the world of Marvel but you probably best know her as Shadowcat. At a glimpse her powers seem pretty lackluster, but then you have to consider just how amazing her prowess with her powers is. So as I am sure you know Shadowcat's power is intangibility, she can pass through pretty much any substance and can pull others through as well as long as they are in contact with each other this includes objects as well (in Wolverine and the X-Men #1 she made the entire Jean Grey School for Gifted Youngster intangible- formal the Xavier school but at least two times as big- including everyone inside so they would not be hit by attack coming their way); the most amazing use of her powers though is the fact that she can also disrupt electrical fields she passes through and can simulate levitation! This way she can do all of this is how her powers work, she basically can pass between the space in between atoms and thus she interacts with molecules around the object which is how she can "walk on air" since she is literally walking on the infinite numbers of random molecules and not those in solid objects, to this same effect she disrupts electrical fields by disrupting the flow electrons in them by passing through and throwing off the flow; this has also been known to be able to effect the flow of electrons in people and causing them to pass out. Another huge pro to having Shadowcat around is the fact she is a genius in the field of computer science, knows countless languages and martial arts, and has a pet dragon that she has a mental connection with that can always sense if she needs help or not (Lockhead) and who doesn't need a pet dragon to help you out at times?