You can't use the Z method for 1 frame DACUS. Because of that, you either have to use C stick to dash attack and then smash up+A in one frame,
OR
you dash attack with A and hit up+up Cstick one frame after the dash attack.
The C stick method is preferred because CStick is the literal ONLY way on standard controls to do an instant dash attack. If you try to do an instant dash attack with A or an alternate attack button, then you get Forward Smash as your input.
Clawing just means that I use my right thumb to press Cstick right, and use my right index finger to press the A button. You are hitting those buttons in a plink motion. It looks like this, but with a GCC.
I think he shows off the Claw method at around ~1:17.
I only use the claw method for DACUS.