I was in the final scene at AZ's grave when all of a sudden I heard the shiny notification when L appeared on screen. I thought it was weird, but considering it made no sense plus it was not a pre rendered cutscene, there was a possibility of a random shiny showing up eventually.
After all the final end card and scene in the hotel I ran back to the graveyard to AZ's grave and found this shiny Gastly! So naturally it is named AZ.
(Please ignore my dripless outfit, I wanted to look as goofy as possible during the serious parts of the game)
by JoeTheMailBox