Black Zero

Black Zero (ブラックゼロ)', also known as Zero Armor and ???, is an upgrade for Zero that appears in most of the Mega Man X series games. It is similar to the Ultimate Armor in that it is usually accessible by a secret code, save for Mega Man X: Command Mission where it is used as his Hyper Mode. Except for Command Mission, this armor is never actually named in-game, and cannot be unequipped in Mega Man X4-X6 once received.

The effects of the Black Zero armor are not consistent throughout the games it appears in. In its first appearance in X4, it appears to be just a facelift. In X5 and X6, it enhances Zero's defense and saber power. In X8, it upgrades Zero's dash and doubles his saber power, but halves his defense. This armor is Zero's only armor in those games, and considerably increases his already great power. For Command Mission, it doubles his attack power, increases his speed by 1.5, bumps up his WE gain per turn by 25% and cuts his fire damage to 75%, but has an extremely short number of usable turns without using Build Hypers.

Unlocking
Refer to the table below for codes used to gain use of Black Zero. The codes are listed with the button pressed and the number of times pressed next to it. In Mega Man X4 and X5, highlight Zero on the Character Select screen and enter the codes. In Mega Man X6 and X8, highlight Game Start, complete the sequence of buttons, and press Start.


 * In Mega Man X5, there is a way to receive the Zero Armor without using a code. In the third station of Sigma's Fortress, there is a vertical shaft that leads to a capsule. Enter the capsule as Zero to gain the Black Zero armor(alternately, X can enter a similar capsule in the same area to obtain his Ultimate Armor). According to the conversation that Zero has with Dr. Light, he (Light) designed the armor for him, and Zero is welcome to either take it or leave it, though Zero claims he doesn't need any upgrades. The Black Zero armor's enhanced saber can destroy energy shots(even Ultimate Armor X's Charge Shot).

Fake Zero
"Sigma, you should have studied the blueprints closer! There is only one Zero!"

- Zero, after destroying his copy

The armor is most likely a reference to the fake Zero in Mega Man X2, where if all three Zero Parts are collected by X, a Zero with black-hued armor created by Sigma appears in the last stage, and Sigma tries to convince X that he is the real Zero. The fake Zero is destroyed by the real Zero shortly after his appearance. If the game is completed without collecting all of Zero's parts, a black Zero will appear after the credits and reveal the Capcom logo. The false Zero also had a brief appearance in Mega Man X5's opening scene. 

Merchandise
Bandai released two different model kits for the Black Armor as part of its Mega Armor model kit series. The first kit that was released featured Zero with pink upper arms and thighs, and purple hair, buster, and Z-Saber. The kit was later re-released and instead featured grey limbs and brown hair, buster, and saber. 

Trivia

 * A form similar to the Black Zero armor appears in Mega Man Zero 2, called the Proto Form. Both have black color schemes, and both have similar effects when equipped.