On an iOS device you can download the app by altering the region settings on your device. First log out of your Apple ID account by opening the App Store app, scrolling down to the bottom, selecting your Apple ID and choosing “Sign Out”. Then go to Settings -> General -> Language and Region -> change Region to US, Australia or New Zealand.
You’ll need to create a new Apple ID for the region that you’ve selected. So that you don’t have to enter credit card details it’s best to do this on a computer. Go to ‘Create Your Own Apple ID’ on a browser to set up a second account. You will have to have a separate email address for the new ID.
Once you’ve entered your details, press “Continue” and follow the steps to verify the account. Then go back to the App Store on your device, scroll down and select “Sign In”. It will ask you to review the new account and suggest you add card details, but you can select “None”.
You should now be able to search for Pokémon Go in the App Store and download it, then sign out of the new Apple ID account and back into your old address.
How to get Pokémon Go on Android