Was so happy that i managed to have the whole thing downloaded without a corrupt file as a result, but it looks like there's a game breaking bug, unless i'm missing something in the install (i didn't forgot to patch the rom, i did it with the lunar ips and followed the mod install intructions twices in case i was skipping a step)
After quickly looking at the impressive amount of wrestlers to see who was new in comparison to 5.5 , i decided to go with a fatal 4 way match (on normal condition).
Started to select Kenny Omega (he's on the AJ Styles slot) and from then it is impossible to do anything else, the game as expected for when i want to select the 2nd guy bring me back to AJ Stykes, but no button work anymore, the game isn't frozen as AJ Styles is still breathing, so no error message unfortunately.
As i had only the "Showdown64" cheats enabled (as instructed), i decided to give a try to enable the "Edit Hacks" in case they were needed but then the game launch with a Fatal Error.
Decided to disable all the interface cheats from inside the Showdown64 main category and while it indeed change the interface a lot , the problem is still occuring, once in Fatal4 ways i select Kenny Omega, it's back to AJ Styles and nothing works anymore.
Tried with other wrestlers and after selecting Steve Austin (on The Rock slot) , back to the same problem (except of course the game is stucj on The Rock)
Same problem happens with Triple Threat (normal conditions) and Tag Team (normal conditions too)
I gave a try to a normal 1 vs 1 match and to my horror, same bug, after selecting Kenny Omega , back to AJ Style and nothing will work anymore
I'm clueless at why it's happening.
EDIT : i found the source of the problem and it's quite surprising to me.
I prefer the nrage plugin to manage my game controls, i never had any problem in any No Mercy mod before with it (including Showdown64 5.5).
But looking at my settings i noticed i had the Controller 2 "plugged" button enabled, odd as i didn't remembered having it on (especially as i play alone on my computer) so bu curiosity i disabled that 2nd controller and launched Showdown64
And it worked without a problem, i could select more than a wrestler as it should.
First time something like that happened to me , so in case someone that like Nrage for the input is running into the same bug, make sure you have only 1 controller plugged because you may accidentally select 2 players in a game instead of only you and all CPU .