Alot of them are soloable (at least I was able to, with some patience) but it does help alot to have someone, if not yourself, who can use Hallowed Ground and pull the path clear for you until they leash the monsters or something haha. I used a guide on XIV Pads to give me tips on what to look out for and what the best routes to the gates were, as well as what monsters aggro'd to which was the most usefull thing by far.

Bottom line, though. Some of them I could not solo, due to lack of patience. I had to use a PLD friend with Hallowed Ground for a few. Tip: "True Sound" or whatever you want to call it, aggro radius is reduced during the rain. As far as I can tell, anyways. I found it alot easier to sneak past boars in narrow Black Shroud corridors when it was raining. ;3