There are 2 FMA games for GBA; produced by Bandai. They were never released outside Japan, and so is kinda hopeless for most to get.
Still, with an emulator like Visual Boy Advance ( http://www.emulator-zone.com/doc.php/gba/vboyadvance.html ) you can play them.
They are like a series, so you should probably play them in order.
Download both games here: http://www.shadyroms.com/index.php?letter=...=GameboyAdvance
They're the 2nd and 3rd from top, since they're listed in their Japanese names:
Hagane no Renkinjutsushi - Meisou no Rondo (J).
Hagane no Renkinjutsushi - Omoide no Sonata (J).
Fullmetal Alchemist: Meisou no Rondo (Stray Rondo)
Translation and walkthrough and everything you need to know: http://www.gamefaqs.com/portable/gbadvance/file/919683/30504
It's really easy and fun once you get into it. I don't know squat Japanese but with the translation page scrolling beside the game, it's all good.
Fullmetal Alchemist: Omoide no Sonata (Sonata of Memories)
Translation etc.: http://www.gamefaqs.com/portable/gbadvance/file/921186/31442
At the moment I haven't played this game, but supposedly it's even better than the first.
Hope this may help some other FMA fans