Guitar Hero On-Tour and Decades both had cart-only releases (although On-Tour's cart-only release wasn't until Decades came out). Modern Hits and Band Hero (and Easy Piano) did not have cart-only releases.
Band Hero's Drum Mode (without using the drum pad, of course), Mic mode and Easy Piano can all be played without any attachments (Easy Piano has an optional touch screen keyboard to play) and thus can be played on any generation DS.
Why do I have all four Guitar Hero games from the bundles?
Well, I bought the first one shortly after it came out (on sale for $29.99 too!)
Bought the other three for $50.
Then got $40 Gift Cards on each of them.
Some really stupid retailer was doing a promo this past Christmas - buy "Any Guitar Hero, Band Hero or Tony Hawk: Ride Bundle, get a $40 Gift Card". Tons of signs posted everywhere.
After talking to a few managers, I managed to get them to honor the deal that said "Any".
Funny part is, they rang up the Gift Card first, then asked "Do you want to just use this gift card on these games?" Well, yeah.