that would be a great solution but that would mean that I should find the PAL .rel and change them one by one. And for most of the maps I don't remember what the .rel is (final destination, battlefield, jungle japes? =/) that would mean a lot of time invested and I'm not ready for that atm

I have found a satisfying solution...: I downloaded WiiXplorer, which let me rename folders on my SD card. I put the files regarding each different version in differents folders. If I wanna change from a version to another, I just have to rename the CODE folder and the RSBE folder so the version I want to play has correct name and the other something inaccurate like CODExx and RSBExx or something like that.

That may seems complicated but I really wanted a solution that only took 1 SD card and no computer. It takes about 5 minutes to do so I'm happy with that!
Thanks all for your input

Oh, now I understand! i didn't know it was possible to customize the iso itself. Thanks a lot for your answers!! 

by hacked iso you mean a normal iso with codes associated with it or litterally a different iso like Super mario bros wii 2?

I have a "normal" partition on my HDD, could I ask ocarina to run the codes from there?

Thanks for your quick answer...

do you think there is a way I could put Brawl - on my SD card and my stages/character hacks on my HDD and ask ocarina to run either one?

I suppose having two SD card would be a solution but I would prefer an easier one =/

Here is my situation:
I changed every stages and most of the character using brawl vault (amazing site by the way!), and I really like the result.
But I recently discovered Brawl - and I find it fun, and I would like if it was possible to choose either version
from my USB loader (The "normal version with new stages/character" and the Brawl - version)

I tried using SSBB ntsc-j but I just realised that .rel files were not compatibles between version, and I don't really want to search for the japanese .rel and change them back one by one. Is there a solution? I heard that there were programs that let us have two copies of the same .iso, could that work? If so, how does I indicate to ocarina which codes should be used for which version?

Any other solution is welcome!
Thanks a lot for your time
English is not my first language so sorry if there are mistakes!