To download the APK file from the APK public site
Since GooglePlay not be able to install from the official site, APK takes a method of introducing download (application body) directly to the terminal.
Pokémon GO 0.29.0 APK Download by Niantic, Inc. – APKMirror
It is possible to download the APK file from the DOWNLOAD APK of the above-mentioned site. ※ It is surrounded by a green frame portion of the screen shot below.
Since all right in any means, to transfer the APK file to the terminal where you want to install the Pokemon GO. (The APK file to attach to send in e-mail, copied to the terminal via MicroSD, using the filer open directly over the network, etc.)
In the case of the author, using the ASUS File Manager, transfer of APK files, it was installed.
File Manager – Google Play Android app
This method is, because it has to get the APK file from the mirror site, there is a possibility that the published illegally modified APK file.
If this is the case, or stolen the information of the terminal, it may be infected with the virus. It is recommended to only use those who can deal with such cases.