I beat the 9-volt battle.
Something I noticed is that you can KO the sherrif, and he's oppressive enough that you should. It does for a lot of the AT battles that some can be defeated, but they are hardy.
It's key to have a strong spirit, preferably legend level with good stats to outmuscle some of these cases. I'm also pretty far in the skill three, and I had the improved dodging ,and the remove the repeated dodging penalty skills unlocked. Combined with getting better stats you can do far more to ''grind'' hard battle. Sometimes it's just best to avoid annoying ones. I also spend some time on the spirit board and with summoning, which does get you some interesting things earlier or easier.
There are more skills that can help then is assumed in some posts too, and quite a few have duplicates in the skill tree and with specific spirits. Your battle strength and and ability to adapt to cheap battle snowballs a bit over time. It takes a while to collect the needed anti-jank stuff. Eventually you can just save a bunch of relevant primary spirits with good supports, and tweak as needed. Just don't stare yourself blind one one fight, and just go do something else.