Can somebody explain Pokerus to me? ^-^

[Dragonstrike]

/Hi, how did you get your faffur looking like that? is ther a new update or skin for the christmas season?

It's definitely a Christmas Mystery Gift.  Seems the event's gone live, but there's been no official announcements yet.  Excited to see the new skins.  Seems the mons are also setup to be competitively viable if you raise them properly, too!