This is a donation Pokemon that is obtained by giving a Sawbuck a Capricorn Scroll to hold. It
was released in January 2012 Parcels, and is the first in a series of Zodiac Pokemon. There was a giveaway that lasted until January 19th.
Everstone%: Can't pass down the sprite. Its nature, however, can be passed down via breeding with a SecretPotion at a 10% chance. Sawsbuck will retain its original form for offspring purposes - so if you use the item on a Spring Sawsbuck, it can breed Spring Deerling if female, paired with Ditto, or holding a Heart Scale.
Shiny%: 10% with Capricorn Scroll, 100% if shiny with Capricorn Scroll.
Other: Can be used for BrightPowder breeding. Will not change forms with the season, and does not have different forms based on its original form.
Natures: Objective, Workaholic, Disciplined or Composed.
(Source)