Successfully complete the game. Then, highlight the "New Game" option and hold L + A. If you entered the code correctly, you will hear a sound.
Successfully complete the game on the hard difficulty setting. Then, highlight the "New Game" option and hold Select + L + A. If you entered the code correctly, you will hear a sound.
Alternate Zero armors
Successfully complete the game on the easy, normal, and hard difficulty settings. Then, press Start and press L or R until you get to a menu with Zero's helmet with a different color. There are pink, black, and red versions.
Using the Whip
Not only can the Whip get far items, but it can also move some heavy cubes and perform a swinging move. Hold B while in the air, and when it grapples onto something, press Left or Right to swing. Release B to let go the Whip.
Gain more level with Chain Rod
Keep hitting on a life or money object to earn more attack points.
Keep returning to The Desert Ambush to gain more 1-ups.
Equip Ultimate Form, then use Buster Shot. Keep pressing Down/Forward + B (for Buster attack). Anything in front of you will be obliterated.
Elemental Chips and Ex-abilities
You can use certain Elemental Chips with Zero's Ex-abilities. There is no need to charge up the Z-Saber (except for the Z-Buster).
Press Up + Attack (similar to Zero's X4 move).
Charged Buster (sparks are left after hitting an enemy)
Press Dash + Attack (a lightning sword pierces through an enemy)
Charged Buster (a ball of electricity)
Press Down + Attack in mid-air (another of Zero's X4 move).
Charged Buster (turns into three rays; X3's Sting Chameleon)
Charged Buster (laser shot in Megaman 8)
Energy Form (Yellow)
Enemies drop more Energen Caps. and Crystal Caps.
Grab 25 Life Capsules to unlock.
Power: ***, Defense: **, Speed: *
X Form (Dark Blue)
Buster becomes more powerful while shooting a charged shot; you can now fire more quickly.
Kill 50 enemies with Buster Gun to unlock.
Power: ***, Defense: **, Speed: ***
Power Form (Purple)
Always biggest saber edge.
Pull anything 30 times with the Chain Rod (even slightly) to unlock.
Power: ****, Defense: **, Speed: *
Defense Form (Light Green)
Damage taken is halved.
Kill 20 enemies with charged Boomerang Shield to unlock.
Power: *, Defense: ****, Speed: **
Active Form (Orange)
Z-Saber is "upgraded". You can now do roll saber attacks, and more damage while jumping.
Kill 20 enemies with Dash Slice attack to unlock.
Power: **, Defense: **, Speed: ****
Erase Form (Magenta)
Z-Saber and Shield can destroy enemy's bullets.
Get 30 ricochets with Boomerang Shield to unlock.
Power: **, Defense: ***, Speed: **
Rise Form (Light Blue)
Up-slash in 3-hit-combo.
Kill 10 enemies with the Z-Saber to unlock
Power: **, Defense: **, Speed: ***
Proto Form (Dark Green)
All weapons at level 1, but major power.
Complete the game to unlock
Power: ****, Defense: *, Speed: **
Ultimate Form (Red)
Allows special key commands for charged weapon
Obtain it by using every Cyber Elf.
Power: ***, Defense: ***, Speed: ***