If my opponent attacks with Dracozolt V's "Primeval Beak" attack, can I still attach Energy cards to my benched Pokemon during my turn?
Yes you may. Primeval Beak only affects the Pokemon that was defending when Dracozolt V attacked.
Source: Evolving Skies FAQ; TPCi Rules Team (2021-08-26)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH7_58
SWSH7_58