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I pretty much agree with all those viability changes, though I'm no expert on ranking mons, I would still say the undead bug deserves to be in the A tier. This is because even if a serious team has one or two answers, another serious player may be able to deal with all of the answers and then...
When M-Ray uses Flying/Ground coverage together the only mons that can resist it are:
Skarmory and Mega-Aerodactyl are the only BH worthy mons and still they tend to be frail against the Mega BH Meta.