Attacks » Dragon's Wish
If I use Dragonair's "Dragon's Wish" attack and then on the following turn evolve it to Dragonite, can I still attach the energies or not?
Yes, absolutely! The Dragon's Wish effect resides on the player, not on the Pokemon.
Source: Sun & Moon FAQ (2017-02-02), TPCi Rules Team (2017-02-02)
Attacks » Dragon's Wish
On the turn after using Dragonair's "Dragon's Wish" attack, when I attach any number of Energy cards from my hand do I have to attach them all at once, or can I attach them whenever I want during my turn?
You do not have to attach them all at once. You can attach them from your hand whenever you like during the duration of your turn following Dragon's Wish.
Source: Sun & Moon FAQ (2017-02-02), TPCi Rules Team (2017-02-02)