Pokerus

I started playing Pokemon Black recently, and just earlier I made it to the Pokemon League. While using the center there, I found out my team had been infected with Pokerus. I had to have contracted it just before healing because only 2 of my team members (Archeops and Ferrothorn) were infected with it.

For how rare Pokerus is, this isn't the first time I got it. I once got it on a Black 2 file I played through almost 10 years ago, and I still have it on there.