I think Nightcrawler is the deciding factor here. His teleportation is very disorienting, combined with his speed and agility makes hit a very tough opponent. There's really no one on the F-5 that can match his power set. Johnny might be the only one that could hurt him, and even that is questionable.
Storm Vs Crystal, I think Storm wins with a lightening bolt. Sue would probably take out Angel with an invisible wall. Colossus, would probably lose out to Ben, not because of strength, but fighting skill. Nightcrawler teleports Reed into unconsciousness. Might take him a while, but I think he could pull it off. Here's the real kicker. I think Johnny is smart enough to stay airborne and away from Wolverine, but probably can't burn him faster than Logan can heal (supernova notwithstanding). This would leave him open to Storm hitting him with enough rain and wind to put out his fire, and Nightcrawler moves in for the win.
This leaves Ben and Sue Vs Kurt, Logan, and Ororo. Sue might be able to suffocate Storm, or play on her claustrophobia with a bubble she can't move in, so she's be unable to focus and use her powers. Wolverine Vs the Thing is a tough call. If Logan got really ruthless, he could slice Ben up pretty badly. Ben's very strong, and could 1 hit KO Logan. I say Wolverine uses his mobility to get in behind the big lug and hamstrings Ben, taking him out of the fight.
That leaves the Invisible Woman Vs Nightcrawler and Wolverine. Her invisibility wouldn't be much use against Logan, since he could probably hear and smell her. Her force bubbles probably couldn't keep Kurt from teleporting. Seeing herself outnumbered, she retreats behind a force bubble, Kurt teleports in, and knocks her out, after asking for her forgiveness.
X-Men win.