Hello there!
I’m trying to setup a tail, and I was wondering if there’s a way to setup stiffness on the markers per axis. I would love to get some really loose follow on the side to side motion, but being able to keep it steady on the ups and downs.
Is there a way to do that?
Hi @betogilardino, welcome to the forums! 
Yes, you can control X (called Twist) and YZ (called Swing) independently, via these attributes per Marker here, under Advanced Pose.
Thank you for the welcome and for the fantastically quick reply!
Will these attributes relate to the rotation stiffness or are independent from it?
Yes, these are multiplied by Rotate Stiffness. If Rotate Stiffness is 0, then both of these will be 0 too.
Fantastic! Thank you very much!
After testing the two attributes, twist and swing, they do almost what I want, specifically the swing one, which loosens the motion of the tail, but as it still does it on two axises, the result is a very droopy tail.
Any other suggestions to achieve a more rigid tail that swings left and right more freely but doesn’t drop down to the floor?
Yes, I can think of one other way, which is to limit the axis you want to see less motion on. Limits also have a Stiffness and Damping and can be tuned in a similar way to Rotate Stiffness and Damping. The limitation being that the values cannot be animated.
Notice how I reduce the amount of rotation it can have on the up/down axis. From here, you can tune the values to achieve the look you want.
That’s fantastic!
I’ll give it a try! Thanks again! And for the screen captures as well!