Versus Mode:

First sucessfully finish the game this can be done of any difficulty setting, this will enable you to unlock versus mode with most stages and five frames.

To be able to unlock the last 2 frames and stages you again need to sucessfully finish on any difficulty setting twice to unlock these.

Alternating Music:

As above again sucessfully finish the game on any difficulty setting but must achieve 'A' Rank on all the 5 rescue missions to be able to hear a different ending tune during the end credits.