In 2nd Encore a new extra added to Skullgirls is the art gallery containing movies and general art of the characters. Simply beating Arcade and Story mode with each character will unlock most of the artwork. Characters who were originally DLC for Encore will also unlock the stages included with their release.

Art/Movie	How to unlock
Bonus Artwork(Fightsicks, Posters, Promotional Material)	Beat Arcade Mode with everyone.
Character's Concept Art	Beat Arcade Mode with the character in your group.
Character's Poster, Story Art and Movies	Beat Story Mode with a character.
Fillia's "Unlimited Hat Works" Joke Scene	Beat Story Mode with everyone.
Marie 300% Cutscenes	Beat Marie 300%.
Stage Art	Beat Story Mode with specific "DLC" character.