UPDATED: Pokemon Go Buddy Update is Live for Android and iOS

During the process of updating a few phones to iOS 10 (work related), I noticed that the Pokemon Go update has now gone live. Immediately, I checked my personal Android and it was there too.
The new update has a few changes, minor bug fixes, text changes, Pokemon Go Plus support, Egg hatching issues (no animation sometimes), but most importantly the ability to assign a buddy pokemon. As always with this game, Niantic isn’t very clear on how this system will actually work, but the premise is that the further you walk with your buddy, the more candy you will get of it’s kind. 
Jump to the Google Play Store and update Pokemon Go as fast as you can, and get to walking!

So it appears that after you set up a buddy, there will be some new screens inside your trainer profile. To assign a buddy: click on your trainers avatar, then the menu at the bottom right, choose “Buddy”, pick a buddy from your list of Pokemon.
To check buddy progress: click on your trainers avatar, then the menu at the bottom right, choose “Buddy”. Now you will see the buddy progress towards earning extra candy. Here you see I would have to walk 3km for 1 candy. That’s a lot of hard earned candy!

From what I can tell from some quick research is that the distance necessary to get a certain candy is tied to the rarity of the Pokemon. More common are 1km (Caterpie), uncommon are 3km (Charmeleon), and rare are 5km (Snorlax). I’ll update this as I learn more.

Here is a list of how far each pokemon has to walk in order to get 1 candy of its kind.

You can change your buddy anytime you want. However, you will lose any progress you have made towards earning candy for your current buddy.