A good way to test if gba carts are authentic, and I know this sounds crazy, but put it in the microwave for like 45 seconds. If the plastic starts to melt around 20 seconds in its fake. The chinese counterfeiters use cheap plastic with a lower melting point. Also if the sparks from the metal contacts interacting with the radiowaves are blue you have a legit copy. The chinese use cheaper metal that produces yellow sparks. If the sparks are blue and it doesnt start melting until about 35 seconds in its authentic. This is the only surefire way to test it. Ive tried it many times.
