Time to learn how to PKHeX. No idea how far you are, if your 3DS has CFW, if you can extract your save file, etc etc.
Get CFW
Dump save file
Open with PKHeX (PKHaX)
Make changes and save
Inject back into 3DS
You'll need to create and inject this locally, it won't be tradable.
Put this pkhax.bat in the same folder as your PKHeX .exe and run it, which should bring you to illegal mode. You can set the ability to Wonder Guard then.
No idea what you did, but the Kangaskhan you have now does not follow jasenyoface's setup. As mentioned, your Origin Game is Sun. jasenyoface's was Red.
IIRC, modify pk*, as in change the current OT (if different) and a few other changes here and there to emulate a trade to your current SAV (if not originating from it).
You need access to Homebrew Channel at minimum, and you might as well fully run b9s if you do.
See https://3ds.guide/get-started-(old-3ds) for your options.