I would definitely have Reshiram at the front of my party once I captured it in Black. Presumably it would have some crazy interactions when you returned to Dragonspiral Tower or the Pokémon League.
I assume Sawsbuck would be very in touch with the season in its' interactions, perhaps catching fallings leaves in its mouth (Autumn) or enjoying cold despite not being ice-type (Winter). Perhaps Electric pokémon and the likes of Klink would have different reactions in that cool cave with all the blue in (I forget the name).