Ghouls'n Ghosts (대마계촌) - Cheats

Options screen

On the title screen, press [Left] [Right] [Right] [Left] [Right] [Right] [Left] [Right] [Right] [Right] [Left] [Right] [Left] [1] to go to an options screen offering a level select, item selection, and the option to have infinite lives or invincibility. Use [1] to decrement and [2] to increment.

(source)

Action Replay codes

00C03302: Infinite lives (keeps showing 2)
00C04C02: Infinite energy

See the main page for Ghouls'n Ghosts (대마계촌)