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.
Source: TPCi Rules Team (2025-10-23)

Relevant cards

Note: All applicable cards may not be listed below.
SM35_3
ME01_10
ME01_10