Roxy didn't like to be brushed for quite awhile either. Patience, persistance, praise, treats, & she eventually accepted it as just part of life. She does real well now. Still not real fond my working on her face, but she's coming along. She used to be more interested in chewing the brush than anything... like the brush part not the handle part. I wondered if that counted as flosssing. lol I didn't like using the slicker brush on her. She doesn't have a real thick coat & the ends of the pins were just too harsh for her skin. If you have a slicker, lightly run it down your arm. Doesn't feel good at all. I eventually got a Chris Christensen wooden pin brush which is the first one I got that I liked. Actually it was a tug-a-war as to whether the brush would for her or me. I let her win, but may get me one too.
I also use a comb on her too after brushing.
Be prepared for a training period for harnesses, collars, & leashes too. Keep at it a little at a time, & he'll get over it. Time & patience.