I absolutely understand the purpose of these tags existing - they serve a generic-copyright tag role, intending to reduce the tag padding that comes from folks being idiotic and tagging the game copyright rather than just the overarching Pokemon tag. In effect, it isn't there to be searched for (even if there some folks searching them), but to act as a solution to a meta-tagging problem. However, as had been brought up at the start, this isn't exactly an issue the Touhou copyrights suffer.
The Touhou copyright wiki clearly states:
NOTE: Don't tag individual Touhou games unless the game is directly referenced by the post. All of the characters in a picture having debuted in the same game is not enough to count. The full cast of a game (with or without the protagonists) appearing will usually count, so long as no other characters are present.
You could easily include such a clause in help:pokemon tags when clarifying on tagging media; in fact, it already does!
A post depicting a Pokémon species is not necessarily a visible reference to any game in particular.
For instance, adding pokemon_swsh to a Wooloo post (post #3528342) would be a mistake, because Wooloo is expected to appear in other media as well.
As a longer example, post #1015491 is a Moltres. It should be tagged gen_1_pokemon. Technically Moltres first appeared in RGBY, but it should not be tagged pokemon_rgby. Moltres can be a reference to any of multiple games and media. It can be captured in multiple games such as FRLG, XD, HGSS, XY, and USUM, not to mention traded to other games. It also appears in multiple manga, the anime, and at least one movie. That's why, instead of using more than half a dozen media tags for Moltres or other Pokémon (which would be technically correct, if impractical), we use just the generation tags as explained above.
Using the Touhou approach would remove the need for that last paragraph - just broaden the previous sentences and you're good to go! Of course, even the Touhou approach has had its own vagueness issues, as per topic #19184, but it is certainly something that works. In fact, if these tags were removed, then you'd effectively got such an approach immediately, thanks to the tag gardening that had been done to make these tags in the first place. If one is diligent enough to tag these, then they're diligent enough to garden without them. And if there are repeat offenders, just slap them with the above-linked help page.
So, while I understand keeping them, given everything, it does unfortunately make more sense to get rid of them and just concentrate one's efforts in gardening directly.
