Enable the "Toggle ghost mode" code. You can go to a place where all the characters are in the part where you stand. For example, you are near the bonus bean room, go through the front doors. You will see characters just standing there in a line. If you are in the great hall at the place with the stairs, go to the hospital wing. Go to where the Spongyfy and go straight through the desk, You will see people standing in a line. You can find a lot of this rooms like the one outside. Go straight through the Diffindo sign until you see people.