I have a buddy who cosplays as Deadpool with another girl as Lady Deadpool. It's a great costume, you can have a ton of fun with it. Personally I'd like to see this version:
Crazy thing about deadpool costumes are... Based on the way deadpool acts and even the way he is drawn sometimes even a bad deadpool costume looks great. I mean if deadpool turned up to an event I think he.would be in a morph suit he bought off ebay
This is probably the best I've seen so far. Generally Deadpool costumes aren't that great from what I've seen. My favorite rendition is Ed McGuiness's version here.