Suggested by Destroyer The Megalodon is possibly large enough to be called a giant monster. This is an opponent who likely could hurt Gigan with his sheer size and power. Of course, Gigan has laser blasts and teleportation on his side which are very valuable to have in a fight. He is dangerous from any range and Megalodon simply won’t be able to endure the onslaught. Gigan even has his Final Wars form if necessary. Gigan wins.