What do you intend your Reshiram for? For more supportive roles, you don't need Modest/Timid, whereas if you're using it for attacking, then those are the best way to go about it. Note that both of them lower Attack, so try not to have Physical moves in its final set.
I only suggest the possibility for defensive Reshiram because Toxic/Tailwind/Roost are all moves seen on it from time to time.
