Do magic eight balls really work?
I dont think so. I think it is just for fun.
For most magickians, there really isn't such thing as black magick, that was just a term coined up by Christianity, using the archetype of black=evil. But, it works by doing a ritual/spell/manifestation causing a negative effect upon another. Other variations are that black magic is magic that uses demons or magic that overrides the will of another.
in emerald i would do duplicating cheats and copy master balls in sapphire i would go with ultra balls,net balls, or timerballs which get stronger the longer your battling kyogre. You can use any type of ball as long as he is weak. It would take quite a few of the normal balls but the Timerballs and the Diveballs work really well against Kyogre