Posting this here as there was no response to my request to post in Policy Review.
I am proposing that we use a Pokemon's usage % at high/top level as a factor in ban criteria. Since it is a factor, there would likely be no threshold for bannability based just on usage percent, and it would depend on other factors like uncompetitiveness, brokenness, and luck-inducing. Even uncompetitive mechanics usually don't have a threshold for bannability by themselves: The ability Arena Trap was banned in SS OU, but Arena Trap Dugtrio is legal in SS Ubers because its other attributes are terrible, and Dugtrio is only C- rank there.
I am suggesting this change because high usage increases staleness, which affects enjoyability. Enjoyability should be a top priority for a game most people don't play for money or to make content. The reason we shouldn't usually make decisions based on enjoyability because it is hard to do so fairly, not because it is not important. As an example, something we can't nerf or ban for enjoyability reasons is Stall, even if most players don't enjoy using or playing it. This is because there is justifiable reason to enjoy Stall and skill involved, including teambuilding to counter stallbreaking methods, playing against Stallbreakers, and Stallbreaking against Stall. I can't think of a good reason why you'd want the top Pokemon to have high usage percent. You'd have to deal with less matchups, but that's not a positive reason by any means as it demotes skill.
I am proposing that we use a Pokemon's usage % at high/top level as a factor in ban criteria. Since it is a factor, there would likely be no threshold for bannability based just on usage percent, and it would depend on other factors like uncompetitiveness, brokenness, and luck-inducing. Even uncompetitive mechanics usually don't have a threshold for bannability by themselves: The ability Arena Trap was banned in SS OU, but Arena Trap Dugtrio is legal in SS Ubers because its other attributes are terrible, and Dugtrio is only C- rank there.
I am suggesting this change because high usage increases staleness, which affects enjoyability. Enjoyability should be a top priority for a game most people don't play for money or to make content. The reason we shouldn't usually make decisions based on enjoyability because it is hard to do so fairly, not because it is not important. As an example, something we can't nerf or ban for enjoyability reasons is Stall, even if most players don't enjoy using or playing it. This is because there is justifiable reason to enjoy Stall and skill involved, including teambuilding to counter stallbreaking methods, playing against Stallbreakers, and Stallbreaking against Stall. I can't think of a good reason why you'd want the top Pokemon to have high usage percent. You'd have to deal with less matchups, but that's not a positive reason by any means as it demotes skill.