To get 5 extra secondary missions: Beat the game once. These missions include some weird battles like two 1993 Mechagodzilla's versus one 1974 Mechagodzilla and even a fight with Hedorah.
Secret Godzilla Dance
To get the Godzilla victory Dance from Godzilla vs Monster Zero: Lose on any stage and wait on the GAME OVER screen. If you wait long enough Godzilla will appear in a little box and start jumping.
