The Buddy feature has been around in Pokemon Go for a long time, and the Buddy Aventure update made some significant changes to it.
For those who are new to the game, the Buddy feature is basically a good way to earn Pokemon candy for your Pokemon. When you select a Pokemon as your buddy, you will be able to walk around with your Pokemon in the game and at the same time develop a bond with them. Apart from the candies, players also get some CP boost and a wide range of other stuff.
Before we jump into how you can play with your buddy, you should first make your Pokemon your buddy. For that, first, click on your Trainer profile at the bottom of the screen and then click on Buddy. Next, you need to click on your current Buddy's image and then press Swap Buddies to change your Buddy. Alternatively, if you are using this feature for the first time, it will guide you about what you can do with your Buddy.
One of the anniversary tasks requires players to play with their Buddy, so if you are looking for that, it is quite a simple process. Simply tap on your Buddy picture at the bottom of the screen and then click on the Play button. Find an open area to spawn your Buddy. Once it spawns, rub on the screen to play with your Buddy, and if your Pokemon reacts to it, it means that the feature is working. If you are able to do it successfully, you should be able to complete the task. You can also give a treat to it by tapping on the berry icon and then throwing the item at it when it spawns.