Tips for easy grinding for Fatality! and Hold On Loosely:
Use Valkenhayn ou Arakune against Tager in local versus, 5 rounds, Infinite time. As a general reference most Forward+C attacks deal Fatal Counter damage since they have high knockback.
For Fatality! (30+ Fatal Counter), use Forward+C and as the move is about to hit Tager press Tager's B (since it's a low kick you risk almost nothing, especially with Valkenhayn who does a hopping kick, if it fails with Arakune use Tager's A since it's a mid attack) on the second controller. Lather, rinse, repeat.
For Hold On Loosely (30+ Throw Reject Miss) it's a bit more tricky, you'll need basically the same settings, but you'll have to remap buttons. I did it with Valkenhayn, but it should work with about everyone:
You're going to need two keys for your main character and one for Tager. So remap B+C to a face button for both characters.
A Throw Reject Miss, as you should know, is a throw performed after a counter against a throw. It's an auto-miss for the victim since any throw break or burst becomes forbidden.
So the trick is to get your character as close to Tager as you can, then press A on your controller, a split-second after (not simultaneously) you press your key for B+C for Tager and as you counter his throw press your B+C key. Lather, rinse, repeat.
With 5 rounds in versus you can grind this easily.
3 rounds are fine as well, just kill yourself with Tager once or twice to make the fight last longer.
The difference with my method compared to most other methods I've read is that you don't need to press Forward+A but just A, which means you can lay both control pads flat and use a hand per controller to get the timing right.
Of course it's nigh-useless outside of the farming, but it might help you understand some timings and hitboxes better.