Hey guys, thank you very much for your replies.
I really don't care about legendaries because I've never really used them, neither in-game nor competitively, but I was just hoping it wasn't like White, where you would just beat the gym leaders and proceed to the next city. Just like you said, there were a lot of locations on the map that are left un-explored...
And btw I have recently got a Reshiram from the GTS, traded it with a level 1 Zorua, lol.
Thank you very much.