If you don't travel, then don't fret. Gen 3 has shown these creatures can swap round occasionally (such as Zangoose and Seviper) or drop regional exclusivity altogether (Plusle and Minun ...

Zangoose and Seviper have a longstanding rivalry with scars to prove it. Born fighters in Hoenn Region. Pikachu and Mimikyu's ...

They do! There are currently a few pairs that have swapped regions since their introduction, such as Zangoose and Seviper.