giving him total choice of options r.e. clothes may be part of the problem- try showing him two outfits and asking him to choose between them, this may reduce the confusion and arguments!
My daughter is exactly the same as this, she throws tantrums every day getting dressed, wrong colour, wrong lenght, anything at all will set her off. She is 5 and this seems to frustrate her just as much as me. She cries and cries in a really distressed way. I have tried everything and am now beginning to think it may be some sort of disorder and am looking into. you are not alone!
Thank you! I am mow trying to ignore him until we have to go to school. Then I take him in the car regardless of how many clothes he has on. He usually gets dressed in the car but has walked in with no shoes and socks on. The teacher is totally supportive of what I am doing which helps.