Pokemon Crystal Cheats

How can I (if I can) cheat to make my Pokemon’s levels grow faster? I just started playing this and my boyfriend and I are having a battle tomorrow….I think he has a gameshark and I don’t know what that is. Any help?
I’m sorry that I don’t play gameboy? Ever? We’re just doing it to goof off…we don’t really do video games. Seriously, is there a way or not? I feel like I’m wasting my time.