I think so. I've never heard anything about two different types of roms.
You cannot just use a slot 2 device by itself, you need to link it with a slot 1 like a CycloDS (which is what I have).
It's so worth it. The price of a CycloDS (which is the best flashcart out) is $47 shipped, which is the price of 2 games basically. Then you get the entire DS library.
And what I'm doing is adding an EZ Flash 3in1, which is a slot 2 cartridge that has rumble, ram (for using internet browser), and plays GBA roms. $18.50 shipped.
So for $65.50 I have everygame from the DS and GBA collections.