You can literally solo adrienn with a duo of good steel types that resist/immune ground. bronzong, magnezone and metagross all come to mind (magnet rise/air balloon) poison types can also corrode the mist field. if you're really desperate there's a few moves like defog and tailwind that can blow the mist away for a fairy tale field, where you can destroy her with steel types.
Thank you! It took me some time to understand how saves and backups work, but I did it and the problem is gone.
I fixed the problem by using an old save (which I didn't know how to until recently). Everything is working fine now.
As for mods and the like, no, I don't use them.