Does Venusaur's "Jungle Totem" Ability boost the damage output of Rayquaza GX's "Dragon Break" attack since "each Basic {G} Energy attached to your Pokemon provides {G}{G} Energy"?
Yes, just because the Basic Energy card is now providing two units of energy doesn't change the fact that it's still Basic Energy.
Source: TPCi Rules Team (2018-08-09)

Relevant cards

Note: All applicable cards may not be listed below.
SM35_3
SM7_109
SM7_160
SM7_177
SM7_177A
SM7_177A