Question

What happens when a Pokemon with Protean uses Flying Press?

Answer 1

The Pokemon, I believe, will become Fighting type. Flying Press's type is Fighting, and its effect is that it deals damage based on the Flying type as well. However, it only receives a STAB bonus for the Fighting type because it is classified as a Fighting attack. Therefore, a Protean Pokemon would become Fighting type.

Hope I helped!

Comments

If it was both then Flying Press would get double STAB from Hawlucha and it would be a super effective hit 100% percent of the time.