If an Evolution Pokemon has been put directly into play by using Greninja & Zoroark GX's "Dark Union GX" attack can I attach Triple Acceleration Energy to it?
Yes, as long as the Evolution Pokemon says "Evolves from..." on it.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)

Relevant cards

Note: All applicable cards may not be listed below.
SM10_107
SM10_107
SM10_190
SM10_190
SM10_200
SM10_200
SM10_201
SM10_201
SM10_222
SM10_222
SM10_234
SM10_234