Hey, I thought of some hints again. xD
-In Hoenn and Unova, the first stage of the fire-type starters does not have flames sprouting from there body, while the other regions' does.
-Both in B/W and R/S, you get the region's common birds late-ish in the game. eg; Pidove is found at Route 3 and Tailow is found in Petalburg Forest. Pidgey, Hoothoot, and Starly are both found early in there respective games.
Those ideas just happen to pop up in my mind. :P