Topic: Is this an original Metroid Zero Mission Cartridge?

The battery is also a dead giveaway that the cartridge is fake. The only GBA cartridges with batteries are Pokemon Ruby, Sapphire and Emerald, and those only controlled the clock. Real GBA cartridges use non-volatile memory for their save data, not battery backup like older cartridges, but a lot of bootlegs use batteries.

I read really early GBA games (like 2001 and maybe 2002) still used batteries.