@Rude i suggest either MoS or mystic.
Mystic is more straight forward. Play at the optimal range of max force push. Bait the opponent to move with instant air soul blast /levitate and hit them with push. Once they are conditioned for push, move in on them. Or continue to play a more footsie orientated game style and don't rush in on them.
Mos is more about pressure and usage of soul ball. You can get way more damage as MoS and generally only need to touch the opponent 2-3 times. Stick on the opponent while conditioning them with pokes and stagger to get a good payout with a 43% meterless combo.does not require a jump in to hit 43%, just a f4 and disciplined execution.
Spectral is under explored but on the surface there seems to be no reason to explore the variation.
Those are the variations in a nut shell. Ermac is complicated and not easy to pick up. He doesn't really have any useless strings outside of b2. Everything else has a purpose