Mewtwo_2000
Smash Lord
Try emptying and formatting the SD card O.oIt freezes after loading the stage (You can hear the Wii loading it). I have an idea of what could be causing it, so I'll give it a shot and tell you the results soon.
Edit: Got the CSS to work, finally, but I tried a stage that used to freeze, and now it still freezes, except the fact that it doesn't do the beep sound anymore.
Sometimes brawl starts acting weird when you're always making direct changes to the filesystem in the SD I guess O.o