With the R-Giga if you plan on using a Tek Bow, take more shards than you think you will need, and HLNA's scan is glitching right now and estimating the Torpor to be lower than the dinosaur actually has/is. If it looks like the Giga is glitched, keep shooting. When you reach the actual torpor rate, it'll KO normally.
Do not turn your back on the Giga once asleep. Do not walk away from it while it's KO'd. The torpor can drop like a rock and no amount of berries or narcotics can max that torpor out again. The torpor drains too quickly. If you walk away, there is a chance your Giga will wake up and eat you. Ideally, make sure you have enough Narcotics or Narco berries to have rows and rows of them. Take a sheep/kibble with you to hunt them so it will be available so you don't need to leave. If you have to step away make it quick and force feed a stack of narcotics before you do so the torpor is going up instead of down. Nothing will Agro to the giga, but stuff will try to eat YOU. Plan accordingly. Happy hunting.
If one is encountered near water, you can simply lure it out to sea with a flyer and it will swiftly drown. Given the water is deep enough. If encountered inland not near water. Pray to the overseers you have something fast enough to out run it. Then promptly die because they're as fast as a mad Hispanic mother with a shoe. Not as deadly as one though.