Sol-Deace

Enable Level Select, then highlight MODE in the Options menu. Hold A and press Right several times. Eventually, the word "MY99" will appear. This option will give you 99 lives.

If you continue to press Right while holding A, the word "MUTEKI" will appear. Selecting this option will make your ship invincible.

On the options menu enable the the level skip and the ninety-nine lives cheat, while the mode says my99, hold down a and keep pressing right until the word "muteki" appears

At the title screen, press A, B, C, A, B, C, B, C, B, A. You will hear a short explosion. Press Start. A Level Select entry will appear on the Options menu.

Enable Level Select. From now on, if you press A + B + C simultaneously you will advance to the next level.

To skip levels while you are playing, enter the ninety-nine lives and level select code. Then hit A, B and C during gameplay to skip a level.