I got hands on experience taming a giga with a pro. Words of advice summed up; get the giga trapped or stuck. On The Island you can use most mountainsides to your advantage. Use metal normal sized dino gates to keep it still (lure it into the trap before adding the last gate). Unlike carno, rex, allo, or yutyrannus running on foot and taking a few bites while knocking out a giga is a recipe for disaster.