try looking in the cheats section for crystal
http://www.supercheats.com/gameboy/pokemoncrystalcheats.htm
sorry, i dont know about gamesharks that well
but make sure you read the instructions clearly and type in the codes correctly...but you dont need codes to finish the game, unless ouy want celebi...
Join this site...http://s14.invisionfree.com/ChaoticRoleplayRealm/index.php?
and this one...http://gameknot.com/?rfr=diezombie...when you sign up the second one, where it says referals by, type in diezombie