Update 9/9/16: The Pokémon Company has now officially confirmed Prof. Oak’s cousin as Samson Oak. Just as predicted from the Japanese trailer, he is a specialist in regional variants of Pokémon. A English screenshot of Samson Oak was also provided:
A Japanese trailer for Pokémon Sun & Moon has just been released, and while it doesn’t show anything too noteworthy, we did get a glimpse at a new character. This character should look quite familiar as well:
That’s right, it’s Prof. Oak! Expect not really as this is actually his cousin, Nariya Oak. He seems to be discussing “Region Forms”, so perhaps his studies involve the Alolan Forms of various Pokémon.
There’s not really much else of note from this new trailer but feel free to check out the full video below: