To the best of my knowledge, those don't exist, as GBA Flashcarts are pretty primitive, and no one really wants to go back to GBA and make one. However, I know that with an EzV 3in1 (GBA Size) you can write a game to NOR and the game will work in a GBA Gameshark.
http://realhotstuff.com is where I got mine.
http://realhotstuff.com/expansion-pack-size-p-212.html Direct link.
You need a Nintendo DS & A DS Flashcart to use this though. GBAExploader also helps :B
honesty didn't get me anywhere