Pokerus lasts forever. The infectiousness is what will go away after 24 hours. That is why you need to keep an infected Poke in your PC, so that you can continue to spread it to your other Pokes.
That's what I'm hoping for! lol
I've done a bit of research on it, and a few tid bits of information...
- I've read that it lasts for either 3 days, or 24 hours. Perhaps it varies, but I've heard more say it's 24 hours.
- You can keep the Pokerus forever by leaving an infected pokemon in the PC.
- As a lead on from the last, one way to conserve it is to put your team players in the PC before you save a shut off, so it pauses the whole scenario for your main pokemon.
- I've read you only gain increased EVs for the time infected, but a lot more say the effects are permanent.
- It appears to be as rare, if not rarer, than a shiny pokemon. I'm not sure the odds for a shiny pokemon (about 1/6000?), but you have, roughly rounding up, about a 1/9000 chance for the Pokerus.
haha, I mean, holy crap. My Mudkip literally got infected on my way up to fight May, before I got to Oldale Town. He was only at level 6. Talk about luck and good timing! And since I rarely carry a 6-pokemon team until near the end of the game, every pokemon I've caught is getting it before I put it in the PC. Some people are saying it spreads after 3-10 battles, but no way. Trust me in saying this thing spreads like wildfire while you're just walking. It spreads like... well, a virus!