Honey's Bonus Outfits (Japanese version only):
Defeat the game on very hard setting in arcade mode. These outfits are selectable in VS., training, and team battle modes.

Invisible Walls:
You must successfully perform 350 moves in training mode to get invisible walls selectable in the options plus menu.

Options Plus Menu:
To access this menu, you must beat the game on Normal mode or harder with any character.

Play as B.M.:
To play as the last boss, Big Mahler, you must win the game on very hard with any character. B.M. is only playable in Vs. mode.

Play as Kumachan:
To play as Kumachan the Bear you must fight 50 rounds in Arcade or Vs. modes.

Play as Mahler:
To play as the smaller version of the end boss, you must beat the game with any character in normal mode.

Thanks to Revolution reader Thomas Wisdom!