Thing is, the only confirmed thing about Fairy is that it's super effective against dragon. Considering most Dragons are 4X weak to Ice, this change doesn't really nerf dragons that much, defensively, and they really didn't need a defensive nerf anyway.
Offense was the problem, and even then, it was more due to the combination of having practically nothing resist it, and having 120+ attacks with few real downsides. While I appreciate stalling being less viable, I think a better solution than making a whole new type (from what we've seen so far; rumors say that Fairy will be immune, but it's not confirmed) would've been to simply nerf Outrage and Draco Meteor. Their current punishments are so meaningless that you basically never see Dragon Claw or Pulse anymore.
Fighting is resisted by Poison, Flying, Psychic, and is useless against Ghost.
Dragon only has Steel to resist it.
It's much easier to switch into Fighting attacks, especially since their most powerful attacks have real downsides as well. (Either lowering user's stats or unreliable accuracy.)
So no, Fighting isn't more OP than Dragon is. Granted, Fighting does SE damage a lot more, but since they had more counters and don't have such blatantly powerful moves, they're not OP. One of the best types to be sure, but not worthy of downgrading a bit like Dragon.
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