Ok got to play some offline casuals (I stopped playing this game online entirely, netcode is too bad to be honest...) against some good players and while not saying this is the best way to play Ermac I would like to share my mindset on how to play this character as a safe zoner.
Still playing MoS, I never end my combo in the 'vortex', rather I end with push if possible and lift if I have to, to gain some distance and start zoning with flight > slam. This might as well be a fullscreen low projectile, it's quite fast, hitbox is the entire screen immediately, do good damge on hit and block (8% on hit, 2% on block how broken is this) and builds him meter. It's hitbox, while being a low, is actually quite high and will catch people midair a lot of times and catch them during jump startup. Thing is, Ermac got some options from flight his opponent must respect and if you got the distance you force them to play your guessing game where you can react for full combo into the same guessing game.
First off, flight dodges a lot of projectiles because of its height, so at a distance they can't really try to play the same zoner game. If they throw a projectile while on the ground and you slam you get a trade, if you do nothing you can just wait then slam when the projectile has passed, and if your reactions are on point you can outright punish with a teleport on reaction for a full combo.
Being in flight gives them a solid reason to come closer (to do anything), either by ground or air. If they dare to jump in to avoid the slam and you didn't slam you can punish jumps on reaction with teleport. Again, for a full combo. This gives them a good reason not to jump, and if they even got close enough to do a jump-in attack on you, the damage you suffer compared to all the chances you've gotten is miniscule, depending on character. This gives them a reason to get by ground and this is where slam is so good, on hit it does 8% and on block, 2%. Regardless of range. If blocked point blank, Ermac is still silly safe.
tldr; at distance, Ermac in flight is a situation that's heavily in favor of Ermac and I try to get into this situation as often as I can and as far as zoning tools go, flight is really good. Opponent have to do at least 2-3 good guesses to even get close to Ermac and the risk/reward favors Ermac.
Exceptions are characters with decent teleports, but you can easily bait this by just going levitate then land and punish.
50/50's are for chumps.
