A thread about how abilities or type changes would be fine (as long as the two were kept distinct and simple, and the OP was given a fair amount of effort), but it doesn't belong in that kind of thread, which is for discussing Hydreigon's actual use and impact.
A fair point; I apologize for stating my opinion like that. However, I still do not think there is any merit at all to a discussion about whether or not Hydreigon is bannable without a Fighting-type weakness, and the post will remain deleted because of that.
It doesn't contribute because it's baseless conjecture with no valuable expansion for discussion, and it is indeed wrong. If Hydreigon magically retained all of its properties besides the Fighting-type weakness it still wouldn't be banned.