Is it against Google Play's terms of service to link to copyright material.

I want to link to full movies on Youtube. is it bannable to have these links in an app?

There is a lot of apps doing this and they’re still alive for a long time on the Play market. Just make sure to write a Disclaimer in your description and in your app.

from which country you will be publishing your apps?

United Kingdom

there are several ways to use youtube by adding disclaimer then do not use any trademark’s…but no one can guaranty when google will ban the app…YES so many apps out there but they are purely based on luck