Just from the linked images alone, the Gen 3 cartridges look legit; it’s a little hard to tell, since they’re pretty low-res, but the background designs are right, all the text is in the right place, and the ESRB rating is proportioned correctly. Do you have a Gen 4 game you could migrate the Pokémon to? That’s one of the best ways to know whether your cart is fake; the bootlegs never get Gen 4 compatibly right. If a Gen 4 game acknowledges the cartridge at all, even if it gives you some error message when to try to actually migrate Pokémon (due to save corruption), then it’s legit.