You don't have to yell! I'm right here!

It doubles EV gains. Good thing. Anything infected keeps it forever, the only thing that goes away is the ability to spread it, so you have to keep a carrier in the PC to keep being able to spread it.

I've gotten it twice, once in Ruby, once in White. How lucky for me.

Your game will function fine, it's something that was intentionally put in the games.

Check out Psypoke's pokerus guide - from what I remember though the chance of your Pokemon catching Pokerus is even more rare than encountering a shiny -- so good luck with encountering it.

You might get lucky like I did and get it from a trade in GTS! or you can just trade with me if you want. Which version do you have?

I've seen 12 shinies but never got any Pokerus...

In Pokemon Gold (my first game), my Onix got Pokerus. I thought it was a bad thing because I thought the Onix evolves when it is at lvl. 50 (i was a newbie) and it didn't evolved while I trained it. I got Pokerus for the second time in Pokemon Black, when I caught a Slowpoke.

pokerus is stupid because you get the stupid face

...honestly? It's one of the best things that can happen. The EV's your Pokemon gains are doubled for a while until it runs off. It's extremely useful when training a Pokemon for competitive battling. So what if there's a little icon on its information page?

the face shows that you cheated and that your pokémon is not happy about it
everyone trades pokérus nobody catches it themself they just play dirty and the face looks bad
train your pokémon honestly and it will look better

^please read this
http://www.psypokes.com/lab/pokerus.php

Pokerus is a good thing and benifits your Pokemon growth and EV's

How is that cheating? It's an actual game mechanic. It's like a bonus round where you get double EVs. There is absolutely nothing bad about it. And trading with someone to receive a Pokemon with Pokerus does happen, but it's not like it's breaking any holy laws of Pokemon.

You sir, obviously are either a very bad troll or a potato.

Can we not call people stupid, please? It's one of those trigger words for me.

Ignorant?

I think everyone will find the replacement better.

Perfectly acceptable and probably correct.

Story time. When I was in the sixth grade, a friend and I were minding our own GOD-FRIGGIN-DANG business at a lunch table, and this dude comes up to us looking to start problems. I don't know why exactly, probably a self-confidence issue, but whatever the case, we ignored him. Until he started calling me stupid, then I lost it and bashed his face into the table and was suspended. (I know, right? That's it?) So, yeah, not real fond of that word for some strange reason that a therapist a few years down the road will probably help me figure out, causing me to reunite with my father after an untold amount of years (untold because I haven't told you) with tears and punches and hugs and more punches and, finally, alcohol. Which will then lead to more punches.

I guess I'll be the potato. And I agree, this face is really horrible, but well, it helps alot in training!
But I personaly dont care so much about heavy training, I have no friends to compete with, or they just sux

Remind me again why we all refuelled a fight that died long ago?

Oh and Twisty, its permanent, even after the contaminating affects are gone, the EV double remains.

My mistake. I had thought that it only lasted the few days, but I guess it doesn't! I'll have to start spreading it through my party when I begin to EV train some Pokemon.

The spreading ability disappear after few days, but if you leave a pokemon in the box, the virus will be "frozen", so the spreading ability will be here forever.

Yes, I understand that. I had just meant about the double EVs. Maybe I'm not explaining this well enough...

I think it only keeps it frozen for a few days. It all actually comes down to the nature I think.

Pokerus only lasts a specific amount of time when in the party, ranging from a couple of days to possibly a week depending on the strain it catches. But if an infected Pokemon is in the box, it won't "age" and be kept indefinitely until it is taken out, and the clock begins to tick again.

the face is your punishment for being lazy and using pokérus
I just don't support it.

Ok, I'm done arguing. Apparently basic logic doesn't exist in this part of the internet.

Twisty: 0
Trolls: 1

Pokérus?

WHY DO YOU THINK IT IS A BAD THING?

You get double EVs! That's awesome! More power! Good. Very, very good. It would never do anything bad to your save file.