Double post, but the thread has been seeing tumbleweeds for nearly a month and I wanna talk, so...
Mechanics idea I speculated about:
- Combo routes AKA typical SoulCalibur gameplay
Landing some of the grounded normals could lead to combos similar in execution to Marth's side B. Unlike side B, the options wouldn't be as numerous, but there'd still be enough to transfer the idea of Soul gameplay into Smash. Mostly 2-hit combos but there could be a 3-hit here and there.
"Button mashing" would be a decent option there, but going out of your way to learn the routes could truly be rewarding, like the games themselves.
- Stance mechanics
When holding the A button after performing any of his tilts, his stance would change.
He'd have three stances. Night Side Stance from forward tilt, Night Behind Stance from up tilt and Night Lower Stance from down tilt. All three stance change his normals completely and even some of his attributes, like Night Behind making him faster and Night Lower putting him on a constant crouch.
If he attacks, gets hit, grabs, gets grabbed or jumps, the stance returns to his default, but there could be ways to retain the stance through holding A in certain combo routes?
Maybe to make things simpler, he could only have the Night Side Stance? Most recent games did that to make him more different than Siegfried.
- Armor Break
So essentially, for those who don't know SC gameplay or need a reminder, ever since SC4, there's been a mechanic where if a part of the body (head, torso, legs) is hit too much, the protective gear would break for that specific part, increasing the damage received every time that body part is hit. And it would stay that way for the rest of the match.
In Smash, the armor would work as a way to reduce damage and knockback, making Nightmare harder to kill but easier to combo as a result, and losing that armor would bring him to how much damage and knockback he'd normally get. As creative liberties, maybe there entire body would count as one part (since it might he harder to tell if stuff like head armor is gone and just simpler overall, like how crafting was simplified for Steve by upgrading all his tools at once) and maybe the armor returns when Nightmare respawns?
DLC so far gave lots of comeback mechanics, so it'd be funny if the devs flipped the idea on its head and gave an advantage mechanic instead.
- Soul Gauge
It's been in both V and VI, so maybe a gauge that allows Nightmare to access a buffed state when filled out?