I really hate the concept of regional pokemon in PoGo, the concept works ok in console games because chances are you know people locally who have one or more of the other games of the same generation. For PoGo though, you are forced to spend heaps of money to travel the world to get everything and there is no guarantee you will find what you’re looking for. Besides this, most players simply do not have a high enough income that would allow them to travel overseas each year, this is why spoofing* is a huge issue. If regionals must exist, then rather than separating them based on countries or climates, why not do a S2 cell based system? For this, you could use size 10 or bigger S2 cells and each one gets a random regional, in the worst case scenario, a player should not need to travel more than about 500km from home to source everything, this would lend itself to day trips or an overnighter or camping, but is a lot more affordable and is doable on a weekend. With this, costs can be minimised by car pooling with other local players.
*For me spoofing itself isn’t the issue locally, but rather the fact that many spoofers often hog gyms and won’t let you have them long, but that’s a different topic.