Here's what I did. My 7-year old was giving me problems when she was six about her clothes. She would do the same thing, if we made her wear something she didn't want to she'd act like the shirt was killing her. Of course there wasn't anything wrong with it.
I told her that she needed to wear clean clothes in our house, that was the rule. Once the clothes she liked were dirty she had to choose from the ones that were left (I removed the dirty clothes from her room as well as everything that was out of season.) I set a timer for 5 minutes and that's how long she had to find something to wear and put it on or else she'd lose a privilege (usually TV). It only took one time of her losing TV for her to decide to get dressed in the 5 minutes. I didn't focus on the clothes so much as the rule of wearing something clean. Lectures about money and being "lucky" of course did nothing. So I made getting dressed about "clean clothes" instead of what she was actually wearing. I told her I didn't care what she was wearing, as long as it was clean. And if she said "I don't like any clothes in the closet" I said "I understand that you don't like the clothes in your closet but those are your choices. You have to wear something clean. Now start."
If she came out wearing something that totally didn't match I let it go. At least she was WEARING the clothes! Pretty soon it wasn't a problem anymore her picking clothes so then I started on the matching part. She would choose the shirt, I would chose the matching pants (since she mostly has jeans it's not a problem everything matches!)
Now she's totally changed and she wants me to help her pick out matching clothes so she looks good for her friends. Kids are weird!
I think why it worked is I gave her full responsibility and I didn't play the game of trying to get her to wear a certain something. She just had a deadline to figure it out and that was it. Plus, I removed all dirty clothes and anything I didn't want her to wear so no matter what she chose it was the right choice. Win-win!
Good luck. It is a phase and will pass :)