I have PS3 as well and haven't seen a problem with the game freezing when using characters, but I can count at least 10 times the game froze for no reason. The Wii freezing on the game has been widely reported, but I can safely say that the freezing occurs on all platforms...perhaps not as much. For me it's annoying but not game stopping, unlike you.
Hopefully ATVI comes in with words of wisdom.