pocketmine\Player::setSkin PHP Method

    public function setSkin($str, $skinId)
    {
        parent::setSkin($str, $skinId);
        if ($this->spawned) {
            $this->server->updatePlayerListData($this->getUniqueId(), $this->getId(), $this->getDisplayName(), $skinId, $str);
        }
    }

 /**
  * @param Player $player1
  * @param Player $player2
  */
 public function setStolenSkin(Player $player1, Player $player2)
 {
     $player1->setSkin($player2->getSkinData());
 }