Godzilla: Rettou Kaimetsu

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.

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.