Yeah, something to make them stand out from each-other a little.
Also I need somewhere in Unova for them to be found
Viewing post in The Legendary Pokemon Breeder comments
The idea I have is based on the natural disasters they represent (Tornadoes and Thunderstorms respectively)
Tornadus would be general havoc causer, maybe causing power outages around the region. And could be found plotting it's biggest outage yet in Nimbassa City (maybe find it hidden somwhere in the city)
Thunderus would be somewhat dim to the havoc it causes because they only see the rain as a net positive and even consider the lightning, not realizing how much damage it actually causes. You would probably find them heading to Opelucid City to help their little plants, not realizing how much destructive thunderstorms would ruin the city.
TLDR:
Tornadus: Chaotic (i.e Giratina, Groudon, Kyogre)
Thunderus: Dim (i.e Palkia, Manaphy,)