Infinite health player 1:
 801232DE 0080

No health player 2:
 80124312 0000

Select all extra players:
 801273D0 FFFF
 801273D2 00FF

Unlimited time:
 80125180 090E

Infinite health player 2:
 80124312 0080

Play as Devil Kazuya (Note 1):
 801C0924 0028

Note 1: This code works by giving you a score of 40 on the Galaga game - to make it work, play
through the Galaga game so your score gets registered and Devil Kazuya is made available.