Adding a wild Pokémon with different forms [FireRed]

Hello,

i am working on a ROM hack with many new Pokémon in it.
And I had the idea of having a bug Pokémon with multiple formes that you can randomly find in the wild.
Like Unknown or Flabébé in newer games.
Does anyone know how to do that? Maybe with the Gen3 Hacking suite?

you need to dig more post in this website ?????? i see it somewhere but forget to save pages ??????

Can be closed.
Dont need the help anymore.

So does that mean you figured out how to do it? I'd love to know.