Hack a Pokémon or a Pokédex entry into a ROM?

[Sawk]

Hi,

I'm playing a Platin-ROM on my emulator at the moment where I have also used a Randomizer. The trainers all have their usual Pokémon, the wild Pokémon are randomized though, and so are the legendaries. As you know, in order to go on after the Pokémon League, you need to have seen all the Pokémon in the Sinnoh Dex. Unfortunately, I don't have the chance to get the Pokédex entry for Azelf, because it was replaced by another legendary Pokémon. 

So my question is: Is it possible to somehow hack the entry or even the Pokémon itself into the game? If not, does anyone have an idea how to solve this so I can proceed in the game to receive the National Pokédex? 

Thank you!