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I feel as though Mega Banette fits in to the description of A rank better. While true, Mega Banette does suffer against common Pokemon, let's look at the description for A rank.
Reserved for Pokemon that are Great in the 1v1 Metagame. These Pokemon have a great matchups against other Pokemon...
Mega Banette from C rank to A rank
I've been playing Pokemon Showdown for a long time now, but I only just made a Smogon account for the sole purpose of posting in this thread (so if I make any small mistakes, try to excuse it. I've never posted before). I've held top position on the 1v1 ladder...