That being said, for Gen 4, there is Bloody Platinum and Flawless Platinum. Both increase difficulty and let you catch all 493 Pokemon up through Gen 4.
Drayano makes good hacks too. He has several. Storm Silver and Sacred Gold (I think those are the names) are hacks of Heart Gold and Soul Silver. Blaze Black and Volt White are hacks of Black and White. Blaze Black 2 and Volt White 2 are hacks of Black 2 and White 2. All of the above mentioned hacks increase difficulty and let you catch every Pokemon up through that generation. There are 3DS hacks too but there is no working 3DS emulator as far as I know so I don’t play them.