I've done AAU ball a few times the last couple of summers....standard gear is an athletic looking pair of black Nike shorts that go to or just above the knee, black low top Nike's (a lot of guys wear their Shox) and black socks (preferably no show or ankle). White socks with all black shoes makes a guy look at least a decade older than he is. In my case, the late 40's/early 50's. Not the image I want to project since I'm already balding on the crown of my coconut.
I'm with Rutledge...avoid the trap of wearing the shorty shorts with accompanying belt/loops.