Changes to Levitate mechanic: more intuitive but probably a bit OP?

[Astefia]

How would the balance of Ground type be affected by these changes?
1. Levitate is not an Ability anymore, but a characteristic of a pokemon species. They are either levitating or not, like they are a certain color or not. Anyone who had Levitate as an ability gets a new ability instead. Yes, the whole Gastly like is levitating except for Mega\Gigantamax Gengar. Yes, Rotom just got stronger.
2. Mud-Slap, Mud Shot, Mud Bomb, Bone Rush and Bonemarang ignore the Flying\Levitating immunity to Ground. Sorry Iono. (Or maybe the last two are Rock or Normal instead? What would be better?)

 

[Vendily]

With respect to 2, Bone Rush and Bonemarang are Cubone and Marowak's signature moves, so I think it'll be a little odd to make them lose STAB.

 

[Scyl]

Free Immunities are always busted.

Free Immunities that don't take up an ability slot are extra busted.