A Pokémon outbreak is probably the most pleasant iteration of the word you’ll come across—it means there is a gaggle of a certain Pokémon concentrating in one area, and you’ll see it marked on your map by a blinking red symbol.
Before you dig in, you should make sure one of your Pokémon has the move False Swipe, PhillyBeatzU says, but once you do, you can start “killing Pokémon, like a normal mass outbreak.” Brutal.