Just fought with Marley against two Team Rocket Grunts outside the Safari Zone. My mother was calling on the Pokégear but I ignored it and went to pick up the Lagging Tail just by. Then, I was going to check my party and pressed "Pokémon" on the menu, but then the screen went black. The music kept playing but otherwise the game froze and I had to hard-reset.
I am using v1.0.4 on a Supercard DSTWO with the newest OS and firmware, and this is the first bug I have encountered in the game (did not have a problem with a Kimono Girl block the dance studio, for example).
EDIT: Pressed "Pokémon" without going into the fight with Marley this time and the black screen occured again. -.-
EDIT2: Talked to my mother on the Pokégear after Marley this time, and the black screen did not happen when opening the party menu. Strange :/