Its functions are somewhat limited, but The Pokémon Company released a photo booth app today for iOS devices.
The app is part of the company's many Pokémon 20th anniversary celebrations. There's not much to it – you can add little captions to your photos that reference Pokémon battles and take a trainer picture. I was hoping you could use it to place Pokémon in your photos, but sadly that is not the case. That being said, however, it is free which means you might as well check it out.
You can download the app here.