Other known variants
+30
-20Wild Growth
Each basic Grass Energy card attached to your Grass Pokémon provides GrassGrass Energy instead. You can't use more than 1 Wild Growth Poké-Body each turn.
Leaf BladeFlip a coin. If heads, this attack does 50 damage plus 20 more damage.
The leaves that grow on its arms can slice down thick trees. It is without peer in jungle combat.
If I have Meganium with "Wild Growth" Ability on the bench and Teal Mask Ogrepon with 2 Basic Grass Energy attached in the Active Spot, can I use its "Myriad Leaf Shower" attack if Nighttime Mine Stadium is in play?
Yes, you can. Wild Growth counts the 2 Basic Grass energy cards as 4 energy, so you satisfy the new attack cost of 4 Energy due to the Nighttime Mine.
If I have Meganium with the "Wild Growth" Ability in play, does my Teal Mask Ogerpon ex's "Myriad Leaf Shower" attack do +90 or +180 more damage if there are only 3 basic energy cards attached to it and no energy on the Defending Pokemon?
You get +180 more damage. When an effect counts "attached" energy you count the total amount of energy including the amount added by abilities like Wild Growth.
If I have both Meganium with the "Wild Growth" Ability and Venusaur with the "Jungle Totem" Ability in play, does each Basic Grass energy count as 4 Grass energy?
No. Each Ability is a replacement effect, not an additive effect. So one would replace the other and you would still wind up with each Basic Grass energy providing 2 Grass energy.