Just to note... what I know about ROM Hacking... is that it's done for your own creativity and storyline of your imagination. Remember, Nintendo will only take action against ROMs and things used to edit their work only if it is still being made. For games such as Pokémon Emerald and earlier games... they are no longer being made. When they become redundant... Nintendo will not take any action against it, because they no longer make any money out of their work anymore.
Remember, they only create things to make more money, and that's only what the company does... is to make more money. So I wouldn't worry about editing a game that is no longer being made. But hey... I also try to edit Pokémon Black as well. ;D
Trust me, if Nintendo really did take action against any of the old games... then PokéCommunity would've been taken down by now.