1- Go to the japanese wiki for touhoumon (search for touhoumon in the english wiki to get a link).
2- Click on Community on the menu on the left.
3- Choose the third option.
4- On point 8, there's a link containing only two characters (reads "koko" if you can read hiragana). Click that.
5-Copy the name of the patch you want in the search engine.
Or search for user Anjirusensei on youtube, he put links to some patches in his videos (Lunatic and Emerald, at least). The Lunatic one also has Johto, the SA dungeon, Dark/LastWord/FullPower touhoumons and places where you can buy every single item in the game, including Master Balls and Rare Candies. It's hard to get through the game, but it's totally awesome.
He's also working on a Lunatic patch for the English version...since last week. Up to now, he managed to include the special touhoumons,
and he fixed the bug where Lunatic hurts you.