Arbok was just banned (thank god) and I'd like to go over the big winners and losers of it leaving the tier.
The Losers:
Being faster than Arbok was a massive selling point in ZU. Teams needed multiple Pokemon that could outspeed Arbok, so Pokemon that were faster than it and otherwise decent gained a massive boost in viability. This doesn't mean they're unviable now, however, in most cases at least. Pidgeot is still probably the best Pokemon in the tier, and Pokemon like Primeape and Ponyta still have strong niches, but besides Pidgeot these Pokemon won't be as plug and play as they were before. The ability to stack more slower and bulkier Pokemon also hurts them.
To contrast the previous group we have Abra. Yeah there's just no reason to use Abra now. Abra's one niche was being able to outspeed Arbok and either KO it after the slightest amount of chip or paralyze it with Thunder Wave. Otherwise, Abra just doesn't have anything. Having no relevant weaknesses doesn't matter when you gets OHKOed by so much, including Pidgeot and Primeape's Hyper Beams, as well as Sandslash's Earthquake. Abra's Speed is genuinely great, but that isn't as important anymore and it critically falls behind the aforementioned Pidgeot and Primeape. Abra hits extremely hard with its STAB Psychic, but it rarely OHKOes anything. And Abra is complete dead weight if it gets paralyzed. We have a Pokemon with an assortment of great tools and stats, but they fall short of making up for its black hole of defensive utility. Will Abra stay terrible forever? I can't say for sure, given how new this meta is. But given that it was fringe when it was the best answer to a very overbearing threat, the future looks quite bleak for it.
While their role in the tier was still being experimented with and optimized, the Rock-types were decent answers to Arbok's Wrap shenanigans, so it leaving hurts their niche somewhat. It's not the end of the world, as they were never that amazing answers to Arbok to begin with, not enjoying Earthquake and theoretically losing to Mega Drain, with them deriving most of their niche by walling Pidgeot, which is still very useful. However, their exact viability is hard to ascertain right now, but they'll likely retain a role in the metagame.
The Winners:
In general, slower Pokemon massively benefit from Arbok's ban, with them no longer having to worry about being worn down by the snake.
In general, the physical walls of the metagame have an interesting dynamic with Arbok. They could very easily lose to Wrap, but generally Arbok didn't want to risk it unless it had to, making them decent checks until the late-game. I would say they benefit solely because it's now much more viable to stack multiple slower Pokemon, so their usage would probably go up.
At the moment it's really hard to guess how ZU will develop, as while it was hell to deal with, Arbok was very much the face of ZU across all its incarnations. However, I do have high hopes the metagame will be balanced, given that nothing seems overbearing now.
ARBOK VR 
