How do I get the Jhoto starter pokemon in Diamond?

I know the only way to get other starters in Diamond/pearl is by migrating, but how do I get Totodile and stuff? I recently started playing Pokemon again and I want the Jhoto starters, so which game do i get them from and how?How do I get the Jhoto starter pokemon in Diamond?
if you wan tthem i would trade you but i want something good just send me a message okHow do I get the Jhoto starter pokemon in Diamond?
you can get them in fire red leaf green then trade them using pal park but you have to catch all the kanto pokemonHow do I get the Jhoto starter pokemon in Diamond?
pal park