Professor Willow

About
Professor Willow is the main Pokémon Professor in the popular Pokémon AR game, Pokémon GO. He appears when a player opens the game for the first time on a new account, and in Special and Field Research. One theory about him that is likely a myth is that he is a younger version of the Johto Pokémon Gym Leader, Pryce.

The main reasoning behind this theory is that Pryce's name in Japanese copies of Johto Pokémon games translates to 'Willow'. In addition, there are many similarities between the appearances of the two characters. For example, they both have whitish hair that spikes forward, and in their official artwork, both of them hold their Poké Balls in the same way.

Conclusion
Although the two characters are similar and most likely the same or connected in some way, we will likely never find out. Pokémon GO does not like to incorporate main series games very often. But it is safe to say that the uncanny resemblance is not a coincidence.