Like with the normal awakening you'll need to be on the ropes at sub 40% health, this requires you to be in a team however. Again charge with
and finish the opponents off.
EDIT: The team needs to be one that has access to the Linked Awakening the same as the Linked Secret Jutsu (for example Naruto and Sasuke, Team 7, Naruto and Hinata etc) forgot to mention this originally as it happened during Story Mode for me.
Also as pointed out by
Wessmonster The storm bar needs to be filled (smaller yellow bar under health) something i again missed as it had been filled everytime I was in need of awakening ^^