I think the gaudy Jusitice-style junk is bought during a very short window when girls are maybe in second to fourth grades and then they're done with the glitter-crusted stuff. That was our experience in school. My daughter was about the only one in her class in fourth grade who didn't wear tons of t-shirts from Justice that were covered in peace signs and slogans and rhinestones. The peace signs still abound and some graphic tees without all the bling, but most girls by now (end of fifth) are wearing plainer t-shirts and jeans a lot. Unfortunately now it's Abercrombie tees -- and I'm not going anywhere near Abercrombie any time soon.
That leaves my daughter still different from them -- she hates jeans or khakis and prefers very soft yoga-style trousers in bright solid colors with matching tops. Fortunately you can get these at Target and sometimes Children's Place, and Target has good, basic solid shirts and nicer polo-style (collared) shirts. It's hard, though, if a girl doesn't want to wear graphic tees with either shorts or jeans every single day -- that is most of what they sell elsewhere.
She's 11 and soon will outgrow Target's kids' section, and I don't know what we'll do then. I see the middle schoolers around here wearing cutoffs, flip-flops and tees to school every day -- not going to happen here.