Here goes...
Mega Abomasnow: Unranked --> B (Ice)
Mega Abomasnow is maybe the most underrated mega ever. With a reason. It has one of the worst defensive typings, having (edit) 7 weaknesses, which are all common or overused (Poison 2x, Bug 2x, Steel 2x, Fighting 2x, Rock 2x, Flying 2x, Fire...