What to do about Royal Guard

QGJ is a good way to remove taunt but that is an out of combat strategy as you may need to acquire him. In combat, remember that RG's taunt happens after the target goes below 50%, so you can burn down a char to about 55%, and then use a character with good burst damage, like Rey or GS, to help kill it. He isn't impossible, he can make your attack difficult if you don't approach him right.