From my knowledge, I believe that there is a READ FIRST thread on this. But while it's here;
The Poke'rus is obtainable in Gold, Silver, Crystal, Ruby, Sapphire, Fire Red, Leaf Green, and Emerald. You get the virus by battiling a wild Yanma. Though there are many wild Yanma in the games, your chances of actually getting the Poke'rus are extremely slim. You'll know if you have it, because when you go to the Poke'mon Center, Nurse Joy will tell you that there seems to be bugs crawling on your Poke'mon. Check your status screen. Congratulations, you have the Poke'Rus. :P
The Poke'Rus raises your Poke'mon's(all six, not just one)stats for a brief amount of time.
And also, it's not such a good idea to make a thread title so long, for if it's too long, you won't be able to tell what it's about on the main page. Try to avoid doing that.