Unlock Maxim Kishine:
Beat the game, then enter MAXIM as your name.
Beat the game, then enter HARDGAME as your name.
Beat the game, then enter NO MAGIC as your name.
Unlock Simon Belmont:
Beat the game to unlock Boss Rush Mode, then press Up, Up, Down, Down, Left, Right, Left, Right, B, A, Select at the Konami logo. You can now play as Simon in Boss Rush Mode.
Playing as Maxim can be tough with having to go to the Save Spots & taking so much damage. But, you can explore to your hearts content and get to a Save Spot at your leisure by going to quiet spot (no enemies) and use the same button combo that you use to summon Maxim's duplicates. Left, Down, Right, Down, Left, B. Don't raise your finger off the button. Just move your finger in the appropriate direction so it is a continuous movement. It may take some practice, but if you see a mass of air bubbles come up & surround Maxim, then you have succeeded.
(supplied by: Lobo Negro)