Yes and I don't know if you played the Grand Travel Map yet. But with some train cards you can remove restrictions. When I first played the 3DS version I used it immidiatly to remove the restricted to option. Some characters -no matter what level- are crap to play! I so hate it when you have to...
OMFG!! YES! Darunia................. I feel your pain. I hate playing as Darunia anyway so I also left him alone and leveled him up. I was able to get that Skulltula with the help of my sister. She and I played it together on the wiiu with a Link level 255 and a Darunia level 80. I'm so glad...
Story Mode hard skulltulas are not that hard to get. The only one that was a pain in the ass to me was the Lake Hylia one in Linkle's story. But it's more about strategy rather than KOs and health. The only thing I can tell you is to do exactly as you're instructed to do to obtain that...