RNG and Pokégen are two completely different things. The former is allowed, the latter is not. If you want to learn about RNG, you can check out Smogon's guide
and the threads in the Wi-Fi forum, or if you don't think you'll be able to learn that in time then I recommend checking out this thread
(even if you'd rather breed the Pokémon yourself, you can probably find good parents from one of the users there - I'd suggest starting with the ones that have Pokécheck links, since the ribbons it adds are irrelevant if you're breeding).