>>48129672If Reshiram and Zekrom represent truth and ideals respectively, then by thematics alone, Zekrom fits N better and Reshiram fits Hilbert better. N fights for his ideals of a world with Pokemon and humans living separately from one another. This ideal however, was based on lies fed to him by his father from his very birth. Hilbert on the other hand, perfectly represents truth. While protagonists are pretty much always silent, we can assume that he's a good and honest boy, and is in fact the very catalyst that reveals the truth to N about the ulterior motives behind Ghetsis' plan.
tl;dr Hilbert fights for truth and N fights for ideals.