Pokemon go needs the Pokemon partner Pokemon to walk next to you in tjhe app like if you agree
And what effect would you like to see, in case that Niantic applies it?
Double kilometers, because there are two players walking? More chances to catch mon’s?
Because the Buddy-System exists, and you get Candies for walking with him…
I think it’s just more of an aesthetic feature; doesn’t need a purpose really. It’s not a priority for Niantic, but it could be something they look into in the future.