The heroes (and villains) are picked somewhat at random from their own storylines, yet it seems at weird points in canon when they have abilities they shouldn't have: like Noctis having (maybe, haven't played him yet) the full Armiger but a pre-chapter 13 personality, Lightning has apparently been picked from XIII in duodecim then in NT she mentions being "chosen" again this time with her LR: FFXIII outfit, WoL is implied that he goes on to LIVE the events of FFI after the events of the original Dissidia (wandering warrior with crystal in hand arrives at Corneria).
Y'shtola has her Heavensward look in the main story, so if her design shifts in 5.0+ we can be sure this is a Shtola taken from between 3.0 and 4.5...

At risk of losing my point in there: tying Dissidia canon with FF canon is a huge headache but I'd love to see what the XIV team can do with a cross-over event.