Rulings

• 2010-03-01
  If the chosen creature is copying something else (for example, if the chosen creature is another Jwari Shapeshifter), then your Jwari Shapeshifter enters the battlefield as whatever the chosen creature copied.
• 2010-03-01
  If the chosen creature is a token, your Jwari Shapeshifter copies the original characteristics of that token as stated by the effect that put the token onto the battlefield. Your Jwari Shapeshifter is not a token.
• 2010-03-01
  Any enters-the-battlefield abilities of the copied creature will trigger when Jwari Shapeshifter enters the battlefield.
• 2010-03-01
  You can choose not to copy anything. In that case, Jwari Shapeshifter enters the battlefield as a 0/0 creature, and is probably put into the graveyard immediately.
• 2010-03-01
  Jwari Shapeshifter copies exactly what was printed on the original creature and nothing more (unless that creature is copying something else or is a token; see below). It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its power, toughness, types, color, or so on.