Scuttlemutt

• WWizards of the Coast2019-07-12
  Official Ruling
  You must choose one or more of the five colors of Magic while resolving Scuttlemutt’s last ability. You can’t choose “artifact,” “colorless,” or “chartreuse.”
• WWizards of the Coast2019-07-12
  Official Ruling
  In the Commander variant, the color identities of cards are determined as the game begins. Changing the colors of a player’s commander doesn’t affect its color identity or the cards that can be legally included in the deck.
• WWizards of the Coast2019-07-12
  Official Ruling
  The target creature has only the colors Scuttlemutt gives it—Scuttlemutt’s ability overwrites any previous colors the creature had.

Rulings via Scryfall