1v1 Council has finished voting on the first slate of bans.
This slate was formatted such that any council member could include a Pokemon for voting if they saw fit. These Pokemon would have been suspected as potentially problematic in the Gen 8 metagame, and either were proven to be so through testing or were shown to not be as problematic as initially thought. To clarify, voting Do Not Ban on a Pokemon on Slate 1 does not mean it could not be considered for a Quickban on another potential slate.
Anyway, with that out of the way,
Just as quickly as they returned, they're back in 1v1 Ubers, where they belong.
Marshadow and Magearna have been quickbanned from 1v1.
Marshadow was never previously tested in the Gen 8 1v1 metagame, as it was clear the pre-Home metagame version of Gen 8 could not handle Marshadow's nearly unrivaled Speed, unresisted STAB coverage, and straight-up unfair unique move, denying setup as a playstyle and going through Substitute. Marshadow had been quickbanned to Ubers in the previous Generation, but with the removal of Marshadow's absurdly strong signature Z move, there was potential for it to be balanced in a Gen 8 post-Legendary metagame. However, it is immediately clear that Marshadow warps the metagame around it - Marshadow's Speed gives it ample opportunity to set up defensively on anything slower, with its functional bulk alongside items allowing it to tank attacks from frail, faster opponents. Even with the emphasis Gen 8 has on Fairy-types, Marshadow has the capabilities to beat back basically anything that does not have this typing, unnecessarily restricting teambuilding. Even its most basic set of Life Orb is a terror in the metagame, and as such it is unanimously banned.
Magearna's ban follows the same old story from its previous ban. To summarize, it has ridiculous coverage, ridiculous utility options, ridiculous bulk, and ridiculous ambiguity. Magearna can be custom made to fit on every team, and can be crafted to beat almost everything in the metagame. Generation 8 has done nothing but shower Magearna with viable options it can use, and not even the onset of new legendaries and viable Fire-types can affect its broken status. For this, it is quickbanned unanimously.
The other considerations for Slate 1 were
Power Construct, Dragonite, Genesect, Jirachi, and Necrozma. Power Construct received a 5-1 DNB vote, and all others were unanimously voted DNB. All Ban/Do Not Ban reasonings for all Pokemon can be found on
this spreadsheet.