If we go with that the photographer should take "natural" photos, then:
A pokemon for aerial transport, like Pidgeott
One for surfing, a big one so the photographer can easly take pictures when riding it, like a Blastoise.
Screw the first gen rule, he needs a Luxray so he can see pokemon hiding or sleeping in their nest etc.
A pokemon with good hearing, I don't know any good example.
He would also need a Smeargle to paint copies of his photos so he can sell them wothout paying for anything else than a sheet.