If you have been playing Pokemon GO since the 3rd generation Update, you may be striking out on finding seviper and thus are wondering where in the you can find this elusive Pokemon. If you fall into this category, don't worry, you aren't alone. The reason for Seviper being so gosh darn rare isn't actually because it has a very low spawn rate, but rather because it is one of many, many Pokemon apart of the 3rd Generation that is Region Exclusive.
If you haven't been playing Pokemon GO for long very long, this means that a Pokemon can only be found in given location on the real world map. In Seviper's case, it can only be found in parts of Europe, Asia, and Oceania. If you don't live anywhere close to these regions and won't be traveling to them anytime soon, this unfortunately means you cannot and will not be able to find Seviper. If your one of the many people that this pertains to, again, don't worry. Niantic has always had the desire to include trading into Pokemon GO, so there's always hope that this will one day come so you can finally get your hands on Seviper.