Currently,if you are in the market for a GBA flashcart,then here are two choices for you.
1.If you are DS users,then you need buy a flashcart with EZ flash 3in1,the flashcart can be any cards that can work well with DSLite,the popular
one cards like r4i gold rts 3ds (http://www.modchipfactory.com/wood-r4i-gold-3ds-flash-cart-for-3ds-xl-3ds-dsi-and-ds-lite-p-1.html),r4isdhc rts 3ds and so on.Here i will named it “A” card.All you need to do is download “A” card kernel firmware and
unzip it,open the folder and copy the root kerne firmware into your micro sd card.Then download GBA Emulator ,unzip it,then put the files
GBA_Exploader.nds and GBA_Exploader.ini into your micro sd card .Creat a “GBA ” folder into your micro sd card and put the GBA games into this folder.
Then insert your “A” card to your DS and power on it to run GBA Exploader ,then insert your EZFlash 3in 1 into Slot_1 to burn the games into EZflash 3 in 1,after
finished,you can play gba games with EZflash 3 in1 card without flashcart.
2.If you are DSi,3DS,2DS users,then you can give supercard dstwo plus a shot.For the time being,it maybe the only one cart that can support GBA games
directly without buying anything extral.Maybe as you knew,the GBA roms supported card like Supercard dstwo and EZflash IV have stopped product and were
not avaiable in the market any more,but the dstwo plus card is the new card by supercard.sc,it with dstwo functions and currently,it is the only
one cart that can support GBA/SNES/DS/3DS games in one cart,so you can use dstwo plus to play gba games without any problems,you just need download the
plug in from official site and unzipped it and put the root files into micro sd card and download any gba games and put the game rooms into micro sd card
as well,then you can play gba games smoothly.