itch.io do ROM hacks now? Interesting twist.
There are various versions of xdelta that are not necessarily mutually compatible and all would have been used at various points during the DS lifetime and could still be being used depending upon the patch maker.
https://www.evanjones.ca/software/xdelta-win32.html is the oldest version and used in some of the oldest patches (Mario Kart, particularly from a site looking like that, being a prime candidate).
http://xdelta.org/ has the 3.0 line which is the current one.
There is a 2.0 line as well.
https://www.romhacking.net/?page=ut...=&perpage=20&title=&desc=xdelta&utilsearch=Go has various utilities that support different versions. I presume that is where you found "every single tool" but I note it anyway.
They do also have an online patcher that might be worth a look
https://www.romhacking.net/patch/
Do also make sure you have the right version - it is an early game so we are not going to be worried by pointless redumps but there is NA, EU, Japan and Korea. NA and EU versions both saw fairly extensive work done on them, though the balance is probably on NA version. Plus the beta releases some liked playing with but I imagine that would be mentioned.
That said I have seen trimmed ROMs from various ROM sites before now as well. To that end make sure the game is 32 megabytes/256Mbit and not less than that.
