If you're not comfortable with downloading APK files or using emulators, consider the following alternatives:
If you want to play Pokémon games on your Android device legally: pokemon ultra sun and moon game download for android apk
The only reliable, actively developed 3DS emulator for Android is . It is an open-source emulator that has made incredible progress, allowing many commercial games, including Pokémon Ultra Sun/Moon, to run at playable speeds on high-end Android devices. If you're not comfortable with downloading APK files