Pokérus

The Pokérus (Japanese: ポケルス Pokérus, likely "Pokémon virus") is a microscopic life-form that may attach to Pokémon, first appearing in the Generation II games.

In the games

Unlike other status ailments, Pokérus cannot be healed at a Pokémon Center or with any status ailment healing item, and can only be obtained by the Pokémon in question once. When a Pokémon has the Pokérus, it gains double the effort values from battling (i.e., fighting a Magikarp will give two Speed EVs, rather than one). Effort points gained from vitamins are not doubled. The infected Pokémon can infect other Pokémon with the virus for a period of about two days. However, the Pokérus timer can be delayed by several methods including placing the infected Pokémon in a PC box.

When it was introduced, the Pokérus had a 3 in 65,536 chance to be on a generated Pokémon, either wild or bred. Through battling or capturing this wild Pokémon, players could get this helpful virus onto their own Pokémon, and subsequently spread it around. Due to the overwhelmingly low chance of encountering the virus (about 1/3 of the chance to encounter a Shiny Pokémon), and the fact that most would not even recognize a Pokémon with the virus and therefore flee from it, many players would never have a Pokémon with the virus.

In later generations, the Pokérus became more likely to get, with several event Pokémon during Generation III having it when transferred into a player's game, and with worldwide trading facilitated by the Nintendo DS's Wi-Fi capabilities beginning Generation IV. In fact, it is common courtesy to infect Pokémon to be traded on the Global Trade Station with Pokérus within some parts of the fandom.

Infection

When infected, a Pokémon's status screen will indicate it much as it does any other status condition (with icon being different for Generation III and IV, while Generation V has the same as Generation IV and Gen II having no icon at all). When another normal status condition, such as Sleep, affects the Pokémon, the Pokérus icon will be replaced. As long as the Pokémon is infected with Pokérus, it can spread the virus to the other Pokémon in the player's party. The infection may spread if the infected Pokémon is in the main party after a battle. An uninfected Pokémon must be next to a Pokémon infected with Pokérus in the main party for the virus to spread. If Pokémon that have already been infected and cured from Pokérus are in the main party and are on either side of a Pokémon currently with the disease, Pokérus will not spread after any amount of battles. Pokémon that are put into the PC will keep the status indefinitely.

After having the virus

Once a Pokémon's immune system has fought off the virus, they cannot spread it further, nor can it be spread to them by other Pokémon. In Generations II and III, a dot will appear on the Pokémon's status screen to indicate that they have had the virus previously, while in Generation IV and V, it will be a small smiley face. Though the virus is gone, its positive effects will remain, most specifically the ability for that Pokémon to gain double EVs.

Any Pokémon on the player's party at the moment the system clock reaches midnight after a certain number of days in that position (number of days depends on the strain and generation) will become immune. An easy way to keep a "vessel" for future spreading is to always send the infected Pokémon to the PC, Day Care, Stadium 2 (in Generation II), Pokémon Box Ruby & Sapphire (in Generation III), or My Pokémon Ranch (in Generation IV) before midnight. The game also recognizes immunizing if the system is turned off and on again on the next day.

In Generation II, if a Pokémon with any stage of Pokérus, active or cured, is traded back to Generation I or withdrawn from Stadium 2 by a Generation I game, all traces of that Pokémon having had the Pokérus will disappear. This is because a Pokémon's Pokérus status is not saved in any form in the Generation I games.

Pokérus is an example of a symbiotic virus (While seemingly oxymoronic, a "virus" is classified by infecting cells, rather than negative effects). Viruses with possible positive effects exist in the real world , but all of Pokérus's known effects are objectively positive.

In Generation II

When the player first encounters the virus in one of the Generation II games, the nurse at the Pokémon Center will make note of it when the Pokémon is first healed after contracting it, saying that there are "small life forms" on the Pokémon. After leaving the Pokémon Center, Professor Elm will call the player to tell them that the virus has no effect and will wear off. As other status ailments, it does not have icon.

Nurse's comments

"Your POKéMON appear to have tiny life forms stuck to them.
Your POKéMON are healthy and seem to be fine.
But we can't tell you anything more at a POKéMON CENTER."

Elm's explanation

"Hello, <player>?
I discovered an odd thing.
Apparently there's something called POKéRUS that infects POKéMON.
Yes, it's like a virus, so it's called POKéRUS.
It multiplies fast and infects other POKÉMON too. But that's all.
It doesn't seem to do anything, and it goes away over time.
I guess it's nothing to worry about. Bye!"

In Generation III

The Pokérus operates in much the same way as in Generation II, though it can infect eggs too. Also, it can only be contracted or cured in Ruby, Sapphire, and Emerald. In FireRed and LeafGreen, as well as Colosseum and Pokémon XD, since the time function is absent, a Pokémon with Pokérus will keep it indefinitely, until it is transferred to the Hoenn-based games. The Pokérus icon is .

In Generation IV

The mechanics remain the same from Generation III. Additionally, much like storage in Pokémon Box Ruby & Sapphire and in the PC, storage in My Pokémon Ranch will keep a Pokémon's Pokérus status indefinitely.

It will also double the effects of the new EV increasing items as well.

In HeartGold and SoulSilver, Professor Elm calls the player a little while after healing their first Pokémon with Pokérus and tells them that it has no effect and will wear off.

If he is called back, he will claim that Pokémon will level up better with the Pokérus while infected. The Pokérus icon is .

Nurse's comments

"Your Pokémon may be infected with Pokérus.
Little is known about the Pokérus except that they are microscopic lifeforms that attach to Pokémon.
While infected, Pokémon are said to grow exceptionally well."

In Generation V

The mechanics remain more or less the same. However, a difference would be that the icon that would appear if a Pokémon has previously had Pokérus would be a pinkish color instead of the former yellow/orange color. The Pokérus icon is still .

Nurse's comments

"Oh... It looks like your Pokémon may be infected with the Pokérus.
Little is known about the Pokérus, except that it is a microscopic life-form that attaches to Pokémon.
While infected, Pokémon are said to grow exceptionally well."

In the anime

In Oaknapped, Professor Namba explained to Professor Oak that the mysterious viral lifeform Pokérus is an important component of the Pokémon Power Acceleration Project (PPAP), a secret project that aims to infect Pokémon with Pokérus to evolve them at a faster rate. However, all of his specimens have died out. Professor Oak also explains that the term "Pokérus" was coined by combining the words "Pokémon" and "virus" together. Later, Professor Oak began researching about the Pokérus.

Trivia

• While all other status ailments are presented on the status screen as small icons in Generation V, Pokérus is still shown with its Generation IV image.
• Pokérus bears resemblance to the Chicken Pox. You can only get the virus once.

References

This game-related article is part of Project Games, a Bulbapedia project that aims to write comprehensive articles on the Pokémon games.