A question about cat grooming?

I have a few cats outside. The one in question is a long haired cat. He recently got in one of those bushes that leave little prickly ball things in his fur. I just tried gently pulling them out, cutting his fur, a bath, and brushing him. Still he's quite nappy. What is the best way to get this out of his fur without shaving him or hurting him in any way?