To sum this up, cyber made a much better and newer version of the 3v3/4v4 mod for Mugen 1.x (aka 1.0/1.1) and WinMugen. I got this off of his blog, which I recommend you go here for the blog post for more information: https://cyber-x64.blogspot.com/2024/
(EDIT: I forgot to add the link for the winmugen version of this so here it is: https://cyber-x64.blogspot.com/2024/05/winmugen-4v4-simul-mode-patch.html)

BUT, if you prefer to read it here. here it is:
Hello my fellow readers.

You probably noticed new engine patches that combine the functionality of 3v3 and 4v4 simul matches have been released for WinMUGEN and MUGEN 1.xx, but before proceeding to download them, you decide to know what makes these engine patches worth it.

Well, you are in the right place to know what improvements my engine patches feature, so let us begin!

(> Adjustable Simul Team Limit <)
Main feature of my engine patches is the adjustable team limit, which allow you to create simultaneous matches with a maximum of 4 characters, so 4v2 or 3v4 matches are now possible in this patch version.

(> Corrected Versus Screen <)
Versus screen is now capable of showing the characters' potraits, while a maximum of 4 player names can be displayed, depending on the engine version.

(> Position Adjustment <)
The other 4 characters will have their position X adjusted to their nearest partners instead of appearing on random locations when a non 2v2 simul match is selected.

(> Reworked AI Control Handling <)
The AI Assignment procedure for simultaneous teams has been reworked in order to allow the player to control a single character while the rest of them are now AI-controlled.

(> Miscellaneous <)
Additional code optimization and bug fixes had to be performed to improve the game experience for some engine patch versions.
4GB Extension is already implemented in these patches.

If you happen to detect any unseen bug while using these engine patches, do not hesitate to let me know it!

Well, this is all for today, so I hope you have found this blog entry interesting to read.

Have a nice day!

Warning:
As expected from engine patches, unpredictable results could occur if known exploits are triggered in this program version, so keep it in mind while selecting your characters.

I am aware engine patches that implement this have already been released, but these patch versions also fix some primary code defects.

Additionally, the 1.1b patch version has been updated to make it compatible with one of the most known add-ons, MUGENHook.

...
There is also a WinMUGEN patch version in case you need it.