it feels like a futureproof way to classify new additions without telling new players that they have an equal role in the metagame as metagame staples.
Sorry I don't get this. Not all mons within a certain tier are staples of it. I wouldn't call Torkoal a OU staple, it just has enough usage for the tier.
Separating the "New" pokemon from the OU doesn't necessarily tell newer players that they're worse than the rest of the OU pokemon
Putting them under the regular OU mons + in a different section absolutely tells newer players that. There is even a phenomenon were mons that start with A are more common than others with similar roles likely because of presentation/reachability bias.Tiers are for determining different levels of usage based on competitive viability, and putting newcomers on a different section artificially affects the teambuilding process.
Also, a lot of the "established OU Pokemon" lose viability with the new additions, so that's another reason for them to not be highlighted over the newcomers.
Furthermore, this is another big issue with the proposal.
If one way or the other people are still "forced" to check in both OU and "New" for an optimal screening of their options, the clutter still exists, just that the order is biased according to the tier status before the new additions dropped.
I could see a "tag", as you mention, for new mons (like a
(new) after their name), but I guess by that point is just informative and doesn't cover OPs objective of reducing clutter.