Jwari Shapeshifter

• WWizards of the Coast2010-03-01
  Official Ruling
  Any "enters" abilities of the copied creature will trigger when Jwari Shapeshifter enters.
• WWizards of the Coast2010-03-01
  Official Ruling
  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.
• WWizards of the Coast2010-03-01
  Official Ruling
  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.
• WWizards of the Coast2010-03-01
  Official Ruling
  If the chosen creature is copying something else (for example, if the chosen creature is another Jwari Shapeshifter), then your Jwari Shapeshifter enters as whatever the chosen creature copied.
• WWizards of the Coast2010-03-01
  Official Ruling
  You can choose not to copy anything. In that case, Jwari Shapeshifter enters as a 0/0 creature, and is probably put into the graveyard immediately.

Rulings via Scryfall