I really like the idea, it seems like a cool idea, however the routes would be massive and you'd be skipping all the smaller towns across Australia like Mildura and Bordertown and all that jazz, but if you could simplify it heaps and just make a region loosely based off Australia it would work great. I like the Pokémon League being in Canberra, too. Great idea.
Just one problem, why is Brisbane bigger than Melbourne? Just geographically wise Melbourne has a larger population, so Sydney and Melbourne should probably have the two town-things-on-the-map-where-it-looks-like-a-square. But yeah, great idea.