Unlock (find the character token) and purchase (in Madame Malkin's Shop) all of these characters AND all their variants (pyjamas, winter outfits, etc).
Harry Potter
Hermione Granger
Ron Weasley
Hannah Abbott
Katie Bell
Susan Bones
Terry Boot
Lavender Brown
Cho Chang
Michael Corner
Colin and Dennis Creevey
Marietta Edgecombe
Justin Finch-Fletchley
Seamus Finnigan
Anthony Goldstein
Angelina Johnson
Lee Jordan
Neville Longbottom
Luna Lovegood
Ernie Macmillan
Padma Patil
Parvati Patil
Zacharias Smith
Alicia Spinnet
Dean Thomas
Fred and George Weasley
Ginny Weasley.
Good luck!