If I have Hiding Energy or Snow Leaf Badge attached to my Active Pokemon, would my opponent's Leafeon VMAX's "Grass Knot" attack do any damage to it or not? If yes, would "Phoebe" remove the effect of Hiding Energy or Snow Leaf Badge for the damage calculation of "Grass Knot"?

The effects of Hiding Energy and Snow Leaf Badge are not blocking any damage from the attacking Pokemon, they are changing the stats of the Pokemon they are attached to. So they are not really affecting the damage done by Grass Knot; it is still 60x the Retreat Cost, but the Retreat Cost is now effectively zero. And since those cards are not affecting the damage being done (they're only affecting the Retreat Cost), Phoebe will not help it do more damage.

Relevant cards

SWSH7_8

SWSH7_159

SWSH3_175

SWSH5_130