>>39734743Only Gengar was an actual nerf. The trio changed the hidden ability, and looks like there are no rules to keep HA (even so I don't know why they decided to change the HA of that trio actually). The other abilities were for Pokemon with one single ability and they gave them the second.
Stats were just adding BST. There are a lot of Pokémon that need to balance the base stats that they currently have because their base stats are already high but there are no cases of this.