To unlock the Abarenbou Shougun Theme and Gmen'75 theme, simply play a song in the multiplayer mode. Only one DS need to have a Band Brothers game card for it to work, however anyone who has the card should receive the two songs. They will both appear in the "TV songs" section. To keep the songs unlocked you must play at least one part of each song.
To unlock Recording Ticket Gold you must beat level 5 in pro-recording studio.
To unlock the Barbara the Bat theme song clear pro-level recording 5.
To get this mode finish all 5 Studio recordings in Special Event.
Get to the pro level in the main game.