I am unzipping PM right now.
Post Merge: January 27, 2016, 01:33:33 PM
Yes. First, delete every custom stage, including the ones that Nintendo made as examples. If you download PM Hackless, put everything on the root of your SD card(I heard that it has to be a 2 GB SD card; I think there's a workaround if it's more than that, but I'm not sure what it is), then, just load up regular Brawl and go to the stage builder; if the screen goes black for a second, then it should load up fine. It may take a few seconds. If nothing happens, try pressing the B button to go back; if you cannot go back, that means that there are either still custom stages, or PM just bugged as it will occasionally do; so delete any remaining stages(If applicable) and try again, and it should work fine. If you CAN go back, however, that means that it's not put in the right place on your SD card and/or it's the wrong size.
I put my SD in with PM Hackless unzipped on the root of the SD, I loaded up Brawl, went to Stage Builder, nothing happened, and I was able to go back to Vault. My SD is a Wii 2.00 Gigabyte SanDisk.