I don't know about this one.
If you would add only frostbite and no drowsy wouldn't it be weird to implement one status condition from legends arceus and don't touch the other one. What will be gained from the addition of frostbite. It is like freeze a secundary effect, so you can't really make a strategy. No one uses flamethrower for the 10 % chance of burn but for the damage. If it happends it is a nice bonus. With the way on how the moves are i really don't see the point to add it, since it is essentially an nerf to a side-effect. I also don't think this game needs it in it's current state. Angie is hard because of her high damage moves and not because the 10 percent change of freezing your mons.
Mayby if you really want strategies around frostbite, then you can make a counterpart to will o whisp, otherwhise the addition won't really add much to the game.
Mayby I am wrong and the new mechanic is way better than freeze, and it will be a huge change to the battle mechanics