If it is someone's personal 'fursona' wearing a nazi uniform in a positive context then it is a promotion of Nazism, full stop.
If, instead, it is a purely fictional character with no ties to anyone (which is where the argument 'it doesn't promote Nazism' holds any water), then utilizing a fictional character in a way in which is to make a counter statement is fair use.
Unless you guys at FurAffinity took all the pictures with Pikachu in it and forwarded it to Game Freak for approval of each one. But something in me doubts that.
If it is someone's personal 'fursona' wearing a nazi uniform in a positive context then it is a promotion of Nazism, full stop.
If, instead, it is a purely fictional character with no ties to anyone (which is where the argument 'it doesn't promote Nazism' holds any water), then utilizing a fictional character in a way in which is to make a counter statement is fair use.
Unless you guys at FurAffinity took all the pictures with Pikachu in it and forwarded it to Game Freak for approval of each one. But something in me doubts that.