Pokey is right about the DS version's Dark Matter being used to fight a superboss (Proto-Babil, a prototype of the Giant of Babil fought by using the Dark Matter on the Moai face on the moon after talking to it and triggering the item menu)
Quote Originally Posted by Jowy View Post
From what I've gathered it didn't affect the damage, just the frequency in which it was cast.
Were you able to find a noticeable difference between having and not having Dark Matter? Because if it is the frequency, that clears things up. I stole it in the GBA version and I didn't see a decrease in damage for Big Bang. I didn't really observe how frequently he casts it, but I did hear somewhere that he shakes before casting Big Bang, if that helps.