I've had the best luck in Eden Beach, Feasterra and Lavalanch. They only come out at night. You can either keep running away until you get a dark knight, or fight all the battles and build up your resources.

My problem is I can rarely defeat them even knowing their weaknesses as well as having the king plug and ring and the chopping blade. The cursor moves way too fast on the final round and I find it almost impossible to get in a hit. Any advice on making them easier to defeat?