My final thoughts on Zama-C are about the same as the first: It's completely fine, and the only reason it's being posited for a ban at all is due to new toy syndrome and people not being prepared for it yet. I'd like to use this post to talk about some things I've seen in regards to Zamazenta-Crowned, both on ladder and arguments in this thread:
1. Defensive teams are more hype than substance.
Despite what a lot of people are saying here, and how it does directly benefit from wish support, semi-stall or full stall with Zama-C isn't really any better than those team styles without Zama-C. While its bulk is certainly impressive, it doesn't really do much of anything on those teams. Usually, you'll switch it in, have it take a hit, then your opponent does whatever they want while you limply hit into their team or click rest and have to be healed again. In my experience using and playing against those kinds of builds, Zama-C was always the weakest component, not the strongest, because it offers nothing to these teams besides an HP sponge when the slot could've been used for a mon that is also fat but actually moves the game forward. It also puts pressure on these teams to constantly heal it, which is different compared to most modern stall teams where everything can recover and this can lead to predictable lines of play, which is something stall really doesn't want.
At the end of the day, Zama-C on defensive teams is nowhere near the end of the world. It doesn't really do anything for the team style that it didn't already have access to, and it won't automatically vault stall to the top tiers of the meta. You're more likely to find Zama-C on offensive teams as a damage sponge than stall.
2. Offense is already adapting to it.
And no, I'm not talking about running something like Vaporeon or Exploud. Besides Volcorona, which Zama cannot touch without another teammate doing most of the heavy lifting for it (and despite people saying Volc on your team makes the stall matchup unwinnable, which is just blatantly false given how volc teams are structured specifically around killing Blissey), Pokemon such as Victini and Aegislash are seeing a rise for their ability to check Zama (Crunch isn't a move people run on it, before somebody brings this up) while still being solid offensive Pokemon with variable sets for whatever your team needs. Helmet Lando-T and Chomp also work as checks as neither of them are OHKO'd by Ice Fang, and despite what some people would claim, SD chomp is still very useful on these kinds of teams. Additionally, Tapu Lele + Hawlucha cores have skyrocketed on offensive teams as they're two frighteningly strong breakers/sweepers that Zama-C doesn't want to switch into directly, which allows them to make progress vs the rest of the team and eventually clean up later. As for pokemon people predicted would be killed off completely by Zama-C, that... hasn't really been the case for a lot of them. While Bisharp is an unfortunate casualty, Rillaboom and Scizor both provide a ton of team support that makes them too valuable to simply stop existing, both commonly run U-Turn and like to click it, and Rillaboom in particular already ran fighting moves on SD Sets for quite some time to hit mons like Ferrothorn or Heatran. Weavile can fit Low Kick onto its SD sets, which at +2 is solidly favoured to OHKO through dauntless shield (98% chance with rocks, 75% chance without), and with adamant being the preferred nature on Zama seemingly Weavile looks to be mostly fine. Low Kick isn't even just for Zama, as it lets it OHKO things like Ferrothorn and Tyranitar that it otherwise would've had to gamble with Triple Axel for.
While offense is still probably Zama-C's best matchup, it doesn't really do anything to it that other anti-offense mons don't already do. There's a variety of checks to it and teams are already being restructured to accommodate it without losing any of their potency, since there's plenty of Pokemon that prevent Zama-C from directly switching into them while still being strong everywhere else, and enough offensive answers to switching into it as well.
3. Most importantly, it doesn't do anything that other things in the tier didn't already do to a degree.
Well yes, something this fast and bulky is new, in terms of how people have "broken" it, it's not anything the tier does not already have. Just about any physical breaker can be broken with the combination of Wish and Future Sight, or even future sight alone. The only reason Zama-C looks so fearsome right now is because it's new and therefore everybody's using it. On the other hand, the fact that it requires that much team support to actually break teams properly is more indicative of its problems than its strengths to me, especially since it's not even unique in that role as things like Melmetal and Urshifu-R can accomplish the same thing. While neither of them are as fast as Zama-C, Zama-C's lacking power means that despite its speed, it often has to take a hit to kill things, even stuff like Ferrothorn which you'd think it could OHKO freely.
Even if it did mythically constrain offense, that's not anything new to OU. Sets like SD Taunt Gliscor 6-0ed stall cleanly in ORAS OU, and it was still allowed in the tier despite a dramatically better matchup vs that team style than Zama-C's offensive matchup. What makes Zama different? That it's against offense and not stall?
Overall, I have yet to be convinced by arguments that Zama-C is unhealthy or broken. It benefits massively from new toy syndrome right now as everyone adjusts to it, but adjustments are being made very quickly, and its hit-taking abilities are pretty overrated and severely limited by the amount of team support it requires to do that all game, at which point you basically have to build your entire team around it just to get results that a lot of other top Pokemon can do much more easily. If it's allowed in the tier, which it should be, I don't see it being any higher than A- on the viability rankings - a far cry from what all the theoryers in the thread say.