Note: The original picture was much higher quality but too large to upload. Tell me a way to supply higher res pic and I will.

As you may or may not know, each Pokemon region is based on a real world location. The first four regions are Japan, Unova is NY and NJ, and so on. At the same time however, the games make reference to real world locations. For example, Surge is the "lightening American", Poliwrath can swim across the Pacific Ocean, and Mew is found in Guyana.

For this reason I am of the opinion that the Pokemon games actually do take place in an alternate version of our Earth rather than a made up place. The Pokemon regions therefore reflect and are located where their real world counterparts would be and the region names are either their universe's name of those countries, or alternative names that also correspond with their given names within the game.

I personally would go with the latter, as it can explain that when Rapidash's Pokemon entry for example says it can leap over the Eiffel Tower, this is actually referring to Prism Tower in Kalos.