Doppelgang

• WWizards of the Coast2024-02-02
  Official Ruling
  If the copied permanent has in its mana cost, X is 0.
• WWizards of the Coast2024-02-02
  Official Ruling
  If the copied permanent is copying something else, then the tokens enter the battlefield as whatever that permanent copied.
• WWizards of the Coast2024-02-02
  Official Ruling
  Any enters-the-battlefield abilities of the copied permanent will trigger when the tokens enter the battlefield. Any "as [this permanent] enters the battlefield" or "[this permanent] enters the battlefield with" abilities of the permanent will also work.
• WWizards of the Coast2024-02-02
  Official Ruling
  The tokens copy exactly what was printed on the original permanent and nothing else (unless that permanent is itself copying something else; see below). They don't copy whether that permanent 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, and so on.

Rulings via Scryfall