The following password will give you three Sub Tanks, four Heart Tanks, the Robot Capsule for the underwater ride armor, and the Air Dash upgrade for your legs. Also, only Gravity beetle is destroyed and Zero is not dead: "4521-4887-6256-1141".
Enter "3367-8683-6772-3875" as a password for all eight hearts tanks, all four sub-tanks (full), all four chips upgrades (X-Golden Armor, inclued Zero Beam Saber) , all four Robots , nine lives, all Bosses defeated, and the final fight for Sigma.
Enter "4746-5186-6258-7747" as a password for all the modifications except for the Saber, and no chips, Bit destroyed, Byte and Vile not destroyed, all the life ups except for the Gravity Beetle life up, and only Gravity Beetle, The Rhino, and the Electric Catfish destroyed. This will allow you to get the majority of the Bosses yourself, and still be able to get the Golden Armor or pick a chip and have all the modifications and maximum life.
Enter "5414-6685-6872-3114" as a password for everything.
Enter "3487-4135-6315-1156" as a password to have all 8 Hearts, all 4 Robot Armors, all 4 Sub-Tanks, all 4 Body Armor parts, no Chips, Bit, Byte and Vile defeated, and no special weapons. You can defeat all 8 Mavericks with a complete advantage over them and will not have to worry about the three HeadHunters because they are already dead.
Enter "8626-4335-6318-7356" as a password for all but Gravity Beetle's heart tank, all armor upgrades(not the Golden Amor), all sub-tanks, all ride-armors, only Tunnel Rhino and Volt Catfish have been defeated, leaving a decent challenge.
Have heal chip
Enter "3217-1383-6772-3821" as a password.
Have arm chip
Enter "1154-2165-6162-7181" as a password.
Have leg chip
Enter "3217-1353-6772-3871" as a password.
Enter "7257-5563-6462-7841" as a password.
At last level fully powered
Enter "6164-4155-6872-3166" as a password.
No upgrades, all weapons, 4 sub tanks, 7 heart tanks, Bit Byte and Vile destroyed, Beam Sabre, and last level
Enter "1455-6863-6427-7185" as a password.
Use Triad Thunder to do more damage while fighting Bit.
Zero's Beam Saber
Defeat Vile with the S. Blades, and have Zero still alive. Play only as X in the first two stages in Dr. Doppler's Lab. In the second stage of Dr. Doppler's Lab, after the water pit area but before the mini-Boss, switch to Zero. Charge up and defeat the "bug". It will fall on Zero, he will be severely damaged, and will give you his Saber. The Saber will be saved with a password.
The Helmet Chip will also fill up the Sub-Tanks, as well as X's main health.
Use the Frost Shield on enemies. Not all enemies will give out power-ups, but most will give out big and small.
Easy extra lives
In the Doppler stage, where you must defeat all the Bosses, shoot the Beam Saber on the standing object. Usually if you shoot on it, healing power-ups will appear. However, if you shoot on it with the Beam Saber an extra life will appear.
Toxic Seahorse level: Change K
Get to the part where you find the Change K, You must have the Air Dash and the Change F to do this. While you are in your Change F armor, jump down into the water and move slightly, but not too far. Make your Change F suit swim to the left, up as far as it can go, then jump out of it. Shimmy up the side of the wall. Next, let yourself slide into the water slightly (while you are still on the wall), then jump towards the end of the ledge holding the Change K. You will not make it, but just when you are on the water tap [Jump]. You will do a jump off the water. Then, slide straight up and you will get the Change K.
To get this upgrade, you must have your X Buster upgrade and Frost S. Once you are in the water, jump past the first hole and stand slightly to the right of it. Power up the Frost S. so you get the shield ability and the thing floats in the water. Jump on it and ride to the top to get Change K.