Very easy way to SSS Echidna with Dante.
I did this on LDK mode, though it should be able to be done on SOS & definitely on DMD.
Have super Dante, switch to gunslinger style, activate devil trigger, have Pandora equipped, triple jump into air and press B bottom (default controls) and keep pressing till she's dead. She didn't hit me at all.
Just to save everyone time this will work for Berial & Agnus, but will not work for Bael (the giant frog), maybe on DMD MODE.