For iOS devices, Angry Birds 2 is optimized for iPhone 5, iPad 3, iPad Mini 2 and iPod Touch 6G or newer. You can try it on older devices, but we can't guarantee a smooth bird flinging experience!
As for Android devices, you will need to have Android 4.1 or later, and your device should have at least a 1.2 GHz processor and at least 1GB of RAM. Angry Birds 2 may work on devices with lower specs, but we cannot make any guarantees. Also, meeting these specifications does not guarantee Angry Birds 2 will run, as compatibility varies from device to device depending on a wide range of other variables.