A2B2

Getting a GBA flash cart, what roms should I legitimately procure for it?

Already getting the Metroid, Fire Emblem and Castlevania games definitely as well as maybe the Final Fantasy ones and the usual Mario Kart and Zelda stuff

advance wars, wario land 4, metal slug, mother 3, megaman battle network(s) 2 & mm zero(s) 2, and ninja five-o. demikids and scurge: hive are apparently good too, but ive never played them.

Golden Sun is a pretty decent JRPG for the GBA

Fire Emblem: The Sacred Stones was my favorite. 
Pokemon Emerald if you're into it. 
Kirby: Nightmare in Dreamland was iconic too.

oh, and don't forget about

*Krazy Racers*
me: mom, can we get mario kart?
mom: we already have mario kart at home.
*mario kart at home*