How do you feel about Fire Emblem? If you likey, there are a couple of GBA titles and I actually recommend you play Sacred Stones first, even though it's the newer of the 2 because it's more forgiving. Also, if you like those check out Super Robot Taisen: Original Generation 1 & 2. Those titles are in the same vein (turn based strategy), but with mechs.
Also,
http://isohunt.com/torrent_details/3...00?tab=summary
Don't know if emulation Roms are what you use for that slot 2 flashcart or not, but this might help with the choices at the very least.