It was never to be registered in the Pokedex, instead they made it simple and made it where it is uncatchable.
ghosts aren't real
Lavender city After Defeating ghosts spirit
you cant go underwater in leafgreen!!
you cant
you cant
you cant.
you cant
cant
you cant
you cant
you cant
you cant get toros on leafgreen you need to catch one on firered and trade it to leafgreen