First introduced in Pokémon Gold and Silver, Pokérus is a virus that the Pokémon in your party have a slim chance of contracting after any given battle. Unlike most well-known viruses, Pokérus is actually one you’ll want to get, as it has no negative properties, and also doubles the rate at which infected Pokémon gain effort values (EVs) following a battle, allowing them to quickly reach their full potential. Here’s how to contract Pokérus in Pokémon Brilliant Diamond and Shining Pearl.
After any battle, there’s a very slim chance one of the Pokémon in your party will catch Pokérus — 3 in 65,536 to be precise. The odds of catching the virus are exponentially higher than the chance you’ll encounter a Shiny Pokémon, and unlike Shiny hunting, there’s no way to lower the odds in your favor. You can check if your Pokémon is infected or not by viewing their summary page; the word “Pokérus” will appear under your Pokémon’s experience gauge if they are infected. Alternatively, nurses at Pokémon Centers will let you know of any infections if you heal at one after being infected.
You’re free to try your luck contracting it through battles, but you can save a lot of time by simply trading for a Pokémon already infected with Pokérus via the Global Union Room. Pokémon with Pokérus are highly sought after in the competitive Pokémon community, and various online message boards are filled with players looking to either give or receive infected Pokémon.
After you acquire one infected Pokémon, spreading Pokérus to the rest of your party is simple. Position the Pokémon you wish to infect either directly above or below the infected Pokémon in your lineup, fight a few trainers/wild Pokémon, and the virus should spread to one of the adjacent Pokémon. Any Pokémon infected with Pokérus will yield double the EVs they would have pre-infection following a battle. For example: Defeating a Spiritomb normally yields one Defense EV and one Special Defense EV. Beating one with a Pokérus-infected Pokémon yields two EVs in those categories.
Pokérus eventually goes away after a few days, but even after a Pokémon is cured, it will still continue to gain EVs at an enhanced rate. However, it will no longer be capable of infecting other Pokémon with this rare, highly-beneficial virus. Thankfully, you can prolong Pokérus’ transmission period by simply placing your infected Pokémon in your PC, where it will remain infected indefinitely until you take it out for a few days.