Roaming Pokémon

Roaming Pokémon are rare Pokémon that can be found randomly while on routes. Each Region has a set of Roaming Pokémon that can be caught. So far, only Mew and Manaphy have no requirements to appear.

Odds
For a breakdown of roaming chances on every route, visit the Route Statistics page.

The chance to encounter a roaming Pokémon is 1/8192 for the first route of a region, and increases linearly up to 1/4096 for the last route of a region."First" and "last" here refer to the health of the Pokémon on these routes, not necessarily the order they are unlocked. This means that a route you can 1-shot will always be at least as efficient as a route you can't, so it is recommended to idle on the highest route number you can 1-shot if you need them. An NPC in each region can inform the player of a specific route in that region where the odds of encountering Roaming Pokémon are tripled. The boosted route changes every 8 hours.  If every route in the region can be one-shot, the Boosted Route is always the best route for encountering Roaming Pokémon.