At first Gamefreak plan to made "Pokemon Follow You" return in SunMoon. That's the reason why we have this animate in game. But they just cancel it before show the trailer at May 2016. Because they finally decide to postpone this to Switch. It will be the "Wow factor" to hype new generation on new console.

So Pokemon follow you won't return in UltraSunMoon. That's all. See ya