Skitterskin

• WWizards of the Coast2015-08-25
  Official Ruling
  If a card loses devoid, it will still be colorless. This is because effects that change an object's color (like the one created by devoid) are considered before the object loses devoid.
• WWizards of the Coast2015-08-25
  Official Ruling
  Devoid works in all zones, not just on the battlefield.
• WWizards of the Coast2015-08-25
  Official Ruling
  Once you legally activate the ability, it doesn't matter what happens to the other colorless creature. The ability will resolve and create a regeneration shield even if you don't control another colorless creature at that time.
• WWizards of the Coast2015-08-25
  Official Ruling
  Other cards and abilities can give a card with devoid color. If that happens, it's just the new color, not that color and colorless.
• WWizards of the Coast2015-08-25
  Official Ruling
  Skitterskin's activated ability doesn't depend on Skitterskin being colorless. If it gains one or more colors, you can still activate the ability if you control another creature that's colorless.
• WWizards of the Coast2015-08-25
  Official Ruling
  Cards with devoid use frames that are variations of the transparent frame traditionally used for Eldrazi. The top part of the card features some color over a background based on the texture of the hedrons that once imprisoned the Eldrazi. This coloration is intended to aid deckbuilding and game play.
• WWizards of the Coast2015-08-25
  Official Ruling
  A card with devoid is just colorless. It's not colorless and the colors of mana in its mana cost.

Rulings via Scryfall