If you're on a land mount and the Giga has you in its sights... you are completely helpless. If you are on a Air mount, stay a good distance above it, as its hitbox is massive, also don't forget to watch your stamina!
On ragnorok there is a spawn place in the grass lands by the light house near the wyvern trench also I used about 40 shock darts and 300 bio toxin on tameing one put be worned a level one wild giga has 80000 health and 100 present melle damage. A tamed level one giga will have 20000 and 25 melee damage . Thumbs up if this has been helpfull to you