If you're carrying a tamed Doedicurus in your claw the Doedic will automatically start harvesting any stones you hover him over. Just start pumping points into your Doedic's weight because it will stop at about half of its own carry weight. I've yet to discover another tame it will work with though...
Be careful when carrying a Dino that has a tribe mate mounted on it. I was walking up a hill carrying my anky with a tribe mate on it and they went under the map and died. RIP ANKY AND SHINEHORN. Tribemate was eh anyway.
The Karkinos is considered a large predator and therefore does not aggro other predators when ridden (with the exception of other karkinos, rock drakes, etc.), making it a great mount for relatively safe traveling!
HOWEVER!!! Smaller predators WILL attack if your karkinos is holding a prey creature in its claws, so keep this in mind while transporting tames and wild creatures!
Alright not exactly my tip, but heard this from the YouTuber pterafier. He said that using a Crab with a Turtle with C4 strapped on it is a good seige device. Put C4 on Turtle, then use Crab to throw the Turtle at a base. Detonate the C4, blowing up the base where the Turtle is at. I'd recommend watching Pterafier, he has a lot of tips on his channel.
No one seems to have mentioned that karkinos can use tools, they just need a special type of tool: doedicurus, use a karkinos to pick up a tamed armadillo and walk around to rocks and the armadillo hits the rocks and keeps them stored, argies and quetz can do it to but they can only hold one and they don't spawn on abberation, not sure but if you transfer a beaver to abberation you might be able to use it and an armadillo at the same time to gather both rock and wood