Cannot be Normal Summoned/Set. Must first be Special Summoned (from your Deck) by Tributing "Zoa" equipped with "Metalmorph".
Rulings
Netrep Q&As
Q: Can you attack with a โZoaโ equipped with โMetalmorphโ and then offer it to Special Summon โMetalzoaโ during the Battle Phase to attack with the newly summoned monster? A: You can only perform that Special Summon during Main Phase 1 or 2 of your turn only. Curtis Schultz, 01/05/2004