Santa Outfit
The Santa Outfit is a purely cosmetic clothing event item available only on the day of Christmas.
Obtaining
During December 25th, the outfit can be obtained by interacting with a Christmas tree that appears at the center of Lux Solis Campus, just left of the decorated Trainer Hub.
If the player interacts with the Christmas Tree they will acquire the Santa Outfit as well as the 
Santa is Coming achievement.
Achievement: (Spoiler alert!)
The Santa is Coming achievement can only be acquired during the Christmas event; if you missed it, you could modify your PC/laptop date manually and set it to the required criteria for the event to start.
When the date is set, launch the game and travel to Lux Solis Campus where you should be able to find the Christmas tree; interact with it to obtain the Santa Outfit and the achievement.
Gallery
Christmas tree and Santa Outfit
