All songs:
Highlight Arcade mode and press Start. Then, highlight any of the difficult settings and press Right, Right, Right, Right, Right, Right
Super mode:
Press Up, Up, Down, Down, Left, Right, Left, Right at the title screen.
Change on-screen characters:
Hold Left or Right, then press Start.
Change playing style:
Hold X then press Start.
Right mode:
At the song selection screen, press Select, Right, Right, Right, Right, Right, Right, Right, Right.
Left mode:
At the song selection screen, press Select, Left, Left, Left, Left, Left, Left, Left, Left.
Shuffle mode:
At the song selection screen, press Select, Up, Down, Left, Right, Down, Up, Right, Left.
Hidden mode:
At the song selection screen, press Select, Up, Down, Up, Down, Up, Down, Up, Down.
Mirror mode:
At the song selection screen, press Select, Left, Right, Left, Right, Left, Right, Left.
Little mode:
At the song selection screen, press Select, Left, Down, Right, Down, Left, Down, Right, Down, Up.
Another mode:
At the game mode selection screen, press Down, Down.
Maniac mode:
Unlock Another mode, then press Down, Down at the game mode selection screen.
Return to normal mode:
Unlock Another mode or Maniac mode. Then, press Up, Up at the game mode selection screen.