This picture is from a request by shikumaru (on FA) for his character and friends dressed as characters from Scott Pilgrim. From left to right, the list is:
rosie_crosswell's (on FA) Rosie as Ramona shikumaru's (on FA) Char Shouhei as Scott tehmoonpaw's (on FA) Lynn as Wallace yuuwolfman's (on FA) Yuu as Stephen