By the way, to get Billy and Saiki's ending pictures, do you have to beat the game with them as the first characters you select?
Because I know I've beaten it with both of them before (even made sure they were on separate teams) but still have not unlocked the pic. However, I noticed last time I played arcade mode, I'd get Ash's ending if he was the first character I select, but not if he was second or third.