Whenever I'm battling in the Fall Festival Zone, it sometimes glitches in a battle and I have to reload the page. What usually happens is after I click an attack for Vermillion, I can't target it against any enemy, so I can't move on to my next Sylesti's move or end my turn, thus stuck in battle. But there's no Stuck in Battle button, so I have to reload the page a couple of times before it works again.

Is there any way to fix this?

I don't think so, not on our end at least. If reloading works, you can do that. If the problem persists, you can post in the bug forum, and Krin will see if he can find the issue to fix.