Successfully complete the game and save it after the credits complete. Start a new game to being with the items obtained in your previous attempt.

Upgrade your Z-Saber skill to the fifth or sixth level to charge it faster. When fighting X second form, use the Ice Chip (obtained from one of your missions), charge your Z-Saber, climb any of the two vertical platforms, and jump-slash towards X's head. Be careful when jumping at X's head as you may hit X's hand.

After defeating Phantom and saving the factory, return to the factory to get a large number of crystals, especially in the last room of the level. Note: You can only get them once.

When inside the resistance, you can always leave and visit past levels. Go up to the surface and move to the right until you get to the pillars that regenerate when they are completely destroyed. Stand next to the wall and charge your Shield Boomerang. Jump and throw your boomerang so that you hit the top section and let yourself fall to the ground. If done correctly, your Shield Boomerang should circle you forever, as long as you do not move. Allow the system to idle for about twenty minutes in this situation to get it to the maximum level.

After completing the introductory level where Zero gets his Sword and Pistol, get on the teleporter and teleport back to the base. Immediately exit the place by trying to climb the ladder you are in front of. Ciel will talk to you, and give you several options to select. Keep selecting the first choice she gives you on each option and you will be teleported to a junkyard level. In the middle of the level there will be these pillars that will keep growing back after each segment is destroyed. You can keep destroying the segments with the Sword and Pistol and they will level-up. Keep destroying the segments until the Sword and Pistol are at their maximum levels.

To maximize the skill level of all the weapons, use them at the enemies at the disposal center; at the part where two spiked things spring up and shoot energy bolts horizontally.
Note: This game is also titled Rockman Zero.

Successfully complete the game, then hold L when starting a new game.

Successfully complete the game in hard mode with an "A" or "S" rank (collect all elves). Start a new game from this saved game to being with all elves including Jackson. Alternately, collect and power-up all cyber elves without using any of them under the normal difficulty setting.

It is possible to dash while using the Shield/Boomerang. Have the shield in hand, then press Dash + Left or Right simultaneously. If done correctly, you should be dash jumping with the Shield. Another trick is to dash jump off walls with the Shield. This is done by holding Dash and jumping onto a wall and climbing it.

Unlock Jackson and start a game. Successfully complete the game using all elves. Hold R when starting a new game to play in ultimate mode.

Note: Some of the steps are in a different order, depending on how you use the weapon.

Z-Buster
Charge
Charge up to two grades
Charge faster
Four shots can be shot at a time
Z-Saber
Double slash combo
Triple slash combo
Charge
Charge faster
Rolling slash combo
Air spinning attack
Triple rod
Double attack
Triple attack
Charge
Charge faster
Shield Boomerang
Middle range attack
Long range attack