Most of the red_(pokemon)_(classic) tags aren't tagged right.

It seems that a majority are Pixiv!Red.

For example, this is not classic: post #542807
But this is: post #933414

What should there be done about this? Deleting the tag off pictures doesn't work.

Maybe we should have red (pokemon) (pixiv) or something like that, to emphasize the distinction? The ones you linked are very similar, with only the different hairstyle and cap symbol.