For nearly two decades, the SNK tag has been a mess, being generally applied to everything made by SNK which is not how the company tags are supposed to be used, but that's something that's generally easy to deal with. As proof of that, earlier this month, I gardened the tag of a lot of these instances and reduced it from 4611 to 2847 posts. But what stopped me from going further was the relationship between the SNK tag with the Fatal Fury and the King of Fighters tags.
The King of Fighters' relationship tagging-wise to SNK is, to draw a parallel, similar to that of Super Smash Bros.'s with Nintendo. While KoF has a prominent original cast, it also features tons of existing characters from SNK's other fighting games, in particular here Fatal Fury, so often you'll have Fatal Fury, King of Fighters and SNK tagged for one character, whether it be two of those tags or all three. And technically, alongside KoF you also have SNK Heroines: Tag Team Frenzy, Neo Geo Battle Coliseum, SvC Chaos, Days of Memories, as well as Capcom vs SNK and Capcom vs SNK 2, which also have SNK tagged, but most of SNK is just King of Fighters art (removing all of the tags mentioned here along with Enta Girl from an SNK search gives you 64 posts, while removing just King of Fighters gives you 179 posts).
So if we want to reduce the amount of posts needlessly tagged SNK, someone has to go through the King of Fighters and garden it, both in relation to itself and in relation to the crossover characters, especially Fatal Fury. If the Capcom tag can resolve this issue, so too could SNK. Shiranui Mai does not need three base copytags, or even two base copytags, when you know someone searching for art of her would just search her tag (so shiranui_mai the_king_of_fighters should just be art that references KoF, or at least art made with KoF in mind, and otherwise her copytag should be Fatal Fury).