Tweaks to make Mega Man X6 more enjoyable. Starting from v14, this patch comes with three variants:

Unlockables
Beating Nightmare Zero on Lvl. 4 unlocks Black Zero. This is coded in the original game, but the original souls requirements for Ranks/events wouldn’t allow it to happen normally (see below).
Reaching Rank UH unlocks the Ultimate Armor.
Cheat Code 1 (Ultimate Armor) now gives both Ultimate Armor and Black Zero.
Cheat Code 2 (Black Zero) has now been repurposed to start the game with Zero available, allowing for a Zero vs. Nightmare Zero match (you can have him earn his Black Zero form himself)
Both cheat codes can be combined.

Parts, Ranks, and Nightmare Souls
Parts are no longer permanently missable. Injured Reploids reappear after getting infected or killed as if you’ve never encountered them.
Parts allowance by Rank has been edited from 0/0/0/1/2/2/3/4 to 1/1/1/2/2/3/4/4 so you can equip at least one part right from the start.
Rank progression has been edited from to 0/200/300/500/800/1500/5000/9999 to 0/200/300/500/800/1500/2500/4000, so Level 4 boss battle start sooner (Rank PA, 2500), and the newly added unlockables of Rank UH can be reached without excessive grinding.
Story scenes unlocked by reaching 3000 are now split and set to match Rank PA (2500) and Rank UH (4000) respectively. As noted above, this allows you to encounter Nightmare Zero Lvl. 4, which isn’t possible in the original game (Lvl. 4 bosses appear at Rank PA, Rank PA requires 5000 souls, but at 3000 souls the game would trigger an event that would make Nightmare Zero not appear anymore).
Dynamo’s Green Orbs drops have been increased from 200 to 600 souls (each). If you’re grinding souls with Dynamo, you might as well get it over with faster.

Game Mechanics
X and Zero now share Heart Tanks, Life Up parts, Energy Up parts, Souls, and Rank.
Blade Armor’s Mach Dash no longer has a delay at the start, has been slightly slowed down for better controllability, and can be cancelled by moving to the opposite direction, just like the regular Air Dash.
Dash and Air Dashes with the Hyper Dash part equipped have been made a bit longer.
Armorless X has now the same defense as the armors, and has the ability to Air Dash, to make him a viable alternative to Falcon Armor at the start of the game (Zero still has lower defense, as his attacks are a lot stronger)
Shadow Armor now also has the ability to Air Dash

Game Mechanics (contributed by Z3R0X)
Zero’s Sentsuizan has been remapped (from Up + Main attack to Up + Secondary Attack) and it’s execution method has been changed to Hold/Release, so you can cancel it anytime.
Height of Zero’s Hyoroga and Shadow Armor’s ceiling jump has been increased (enough to reach Rainy Turtloid’s ceiling)
X’s Saber’s speed has been slightly increased.
Shadow Armor’s Saber can be cancelled by alternating it with dashing, just like the regular one.

Damage Charts
Blade Armor’s moves deal a bit more damage against all enemies.
Nightmare Snake (aka Donuts) receive about x4 damage. Should be a bit faster to take down.
Complete: A heavier cut of annoyances and other tweaks. Recommended for repeated playthroughs.

Plus
Disables all “Nightmare Effects” (hazards on stages activated by the previous stage visited)
“Exit Stage” button always available
Disables Alia’s alerts and other dialogues inside stages (all except dialogues with bosses)
Disables Stage Select screen dialogues stages
All injured Reploids not holding any items are marked as “MISSING” at the start of the game, drastically reducing the number of Reploids clogging stages (keeping only the ones that matter).
Disables injured Reploids giving extra lifes. Instead you get a consistenly higher number of lives (from 2 normal/4 with EX Tank, to 4 normal/6 with EX Tank).
Nightmare Virus’ Blue Orbs will always appear (would normally reappear only after a Nightmare Effects has been activated for the corresponding stage)
Blue Orbs left alone not turn back into a Nightmare Virus

Uber Blade Armor: Just for fun
Blade Armor available from the start
Blade Armor’s Mach Dash mechanic changed to Hold/Release, with unlimited duration. Can be repeated all you want on a single jump. Deals as much damage as the Nova Strike.
Can now start any air move after a dash jump.