If you're trying to complete the Pokemon Go Pokedex without any help, then it isn't going to happen unless you're a keen traveler. Various species from each generation can only appear in certain regions across the world. These are known as regional exclusives.
If you really are going to complete the Pokemon Go Pokedex by yourself then traveling is your only option. However, there is another method, which is getting those regionals by trading.
This, of course, does cost precious Stardust. If you are going to get them via trading, then try and make sure you're Best Friends or live close to each other, as this will give you a big discount.
Special regional events
Sometimes Niantic creates Pokemon Go events that let you catch previous unobtainable regional exclusives. These events are only temporary however.
For example, the Gen 1 regional exclusives could all be found in eggs as part of the second week of the Ultra Bonus Rewards from GO Fest 2019. There are other examples too, and there will almost certainly be future opportunities as well.
List of all regional exclusives
For the moment though, some Pokemon can only be found in certain regions. The full list of these, divided by Pokemon generation, is as follows:
- Tauros - North America
- Mr Mime - Europe
- Kangaskhan - Australia
- Farfetch’d - Eastern Asia
- Heracross - South and Central America
- Corsola - Near the equator
- Torkoal - India and South Asia
- Zangoose - Europe, Asia, and Australia
- Seviper - North America, South America, and Africa
- Solrock - North America, South America, and Africa
- Lunatone - Europe, Asia and Australia
- Relicanth - New Zealand and surrounding areas
- Illumise - Europe, Asia, and Australia
- Volbeat - North America, South America, and Africa
- Tropius - Africa
- Pachirisu - Alaska, Canada and Russia
- Shellos - East of Prime Meridian Pink, West of Prime Meridian Blue
- Chatot - Southern Hemisphere
- Carnivine - Southeast US
- Uxie - North America, South America, and Greenland
- Mesprit - Europe, Middle-East, Africa, and India
- Azelf - Asia Pacific
- Pansage – Asia Pacific
- Pansear – Europe, Middle East, Africa, and India
- Panpour – Americas and Greenland
- Heatmor – Western Hemisphere
- Durant – Eastern Hemisphere
- Sigilyph – Egypt
- Throh – North America, South America, and Africa
- Sawk – Europe, Asia, and Oceania
- Basculin – Eastern Hemisphere Red, Western Hemisphere Blue
- Maractus – Central America, South America, and the Caribbean
These can change at anytime but for the moment the above are regional exclusive Pokemon. Alternative, if you really don't want to wait for events or trade with other Pokemon Go players, you can just transfer them over from another Pokemon game via Pokemon HOME!