I'm from Asia.
This time, tested some of the Mega Man X6 Tweaks Patcher (v04c) using emulator ePSXe 2.0.5.
I only test whatever new and bugs that occured in v03a.
1) Nightmare Effects
Bugs (Commander Yammark) = Disable Nightmare Effects on Blaze Heatnix's and Shield Sheldon's stages.
Ice (Blizzard Wolfang) = Disable Nightmare Effects on Metal Shark Player's stage.
Fire (Blaze Heatnix) = Disable Nightmare Effects on Blizzard Wolfang's (ice wall still break and enable secret area) and Infinity Mijinion's stages.
Iron (Metal Shark Player) = Disable Nightmare Effects on Blaze Heatnix's, Ground Scaravich's and Infinity Mijinion's stages.
Cube (Ground Scaravich) = Disable Nightmare Effects on Metal Shark Player's and Shield Sheldon's stages.
Rain (Rainy Turtloid) = Disable Nightmare Effects on Commander Yammark's and Ground Scaravich's stages.
Mirror (Shield Sheldon) = Disable Nightmare Effects on Blizzard Wolfang's and Rainy Turtloid's stages.
Dark (Infinity Mijinion) = Disable Nightmare Effects on Commander Yammark's and Rainy Turtloid's stages.
I only tested it once each. Yeah, should be working fine.
However, I forgot to test if disable 1 Nightmare Effects may disable other Nightmare Effects.
Will try it again later if got time.
2) Characters Shared Stats
Both Life and Energy Upgrades, and Nightmare Souls and Rank are working perfectly now.
3) New Game Status
a) Parts and rescued reploids
Only tested the normal parts. I don't have enough time. Will feed back again later.
Speedster = Reploids rescued (Tsuki from Central Museum) is correct but gets Hyper Dash.
Jumper = Reploids rescued (Dante from Northpole Area) is correct but gets Jumper and Hyper Dash.
Speed Shot = Reploids rescued (Tekk from Weapon Center) is correct but gets Buster Plus and Speed Shot.
Shock Buffer = Reploids rescued (Toshi from Recycle Lab) is correct but gets Buster Plus and Shock Buffer.
D.Barrier = Reploids rescued (Kenz from Laser Institute) is correct but gets Buster Plus and D.Barrier.
D-Converter = Reploids rescued (Paralla from Weapon Center) is correct but gets Buster Plus and D-Converter.
However, if you tick all the normal parts, you get all the 10 normal parts plus the correct 10 Reploids rescued.
b) Characters Available
By using this patcher, you'll permanently disable from getting Ultimate if you use the left, left, left, right code.
You can only get to play the intro stage as Ultimate.
Same goes to Zero (Black). Cannot be activated with L1, L1, L1, R2 code.
However, you might still get Zero (Black) by beating Nightmare Zero lv4.
You will still keep Falcon.
After intro stage, Blade/Shadow will be available.
A full armor parts is collected without affecting the game mode level.
No more armor parts capsules for the specific characters.
The game still starts as Falcon but you'll be able to keep Ultimate after intro stage.
Tick Zero/Zero (Black):
After the intro stage, Zero/Zero (Black) will be available.
However, you'll skip the optional boss fight 1 (Nightmare Zero) and move on straight to optional boss fight 2 (High Max).
c) Life Upgrades, Energy Upgrades, and Rank
All are working fine as stated.
However, if Characters Shared Stats was activated, and X and Zero was having different value, the patcher will always follows X's stats.
eg. Characters X Zero
Life Upgrades +12 +8
Energy Upgrades +0 +4
Rank A D
Then, the outcome you'll get is:
Characters X Zero
Life Upgrades +12 +12
Energy Upgrades +0 +0
Rank A A
Also, the nightmare souls you have will be the value you set for Rank A.
In this case, if you did not altered the Nightmare Souls and Ranks, Rank A = 500.