If you want to catch all the Pokemon in Pokemon Go, you might have to do a bit of traveling. A report from the Serebii fansite claims that four Pokemon in Pokemon Go are exclusive to one continent. Per the report, Mr. Mime is exclusive to Europe, Tauros is exclusive to North America, Farfetch'd is exclusive to Asia, and Kangaskhan is exlusive to Australia.
There is one giant caveat in these region exclusive Pokemon, in that all four Pokemon are still able to be hatched from eggs. All four can be hatched via 5 KM eggs, meaning that players have a 1 in 43 chance of getting one of the three Pokemon not catchable on their continent simply by walking around.
It's unclear how Serebii first came upon this report, but Serebii siterunner Joe Merrick has been open on Twitter about trying to determine its accuracy.
Pokemon Go is currently the top selling app in US history, despite server issues that have plagued the game since its release. The game was recently released in multiple countries and Canada, but was hit by two separate DDOS attacks that crippled the servers for much of the weekend.