If it's transformed in your hand and you emote it transforms again. Also it transforms when you click the emote if you can't use it because you BM'd too much. The Sorry one is available only with Noggenfogger.
mostly based on chinese new year and chinese zodiac(12 animal cycle including a dragon) lore. transform effect may cancel enemy attack because it also give summoning sickness, putting it on deathrattle taunt gives it strong defense value but may backfire if enemy minion transformed into stronger ones