At last! After several weeks of waiting, the successful Pokémon GO has officially come to Latin America, but yes, for now only some countries like Mexico.
While it is true that the application could be downloaded from the App Store from another country, that is available in countries like Mexico or Brazil will result in the game to work much better than before thanks to have its own servers.
Pokémon GO ✔ @PokemonGoApp
We are excited to share more details about #PokemonGO including the launch across Latin America! https://goo.gl/pxHfmW