My Luxray has a little marble icon that says "this pokemon appears
to have a special power."
I looked up what this means and it said it meant they could mega
evolve, but that only pokemon with canon mega evolutions would get
it.
Any clue why a luxray would have it?
Thank you!
It seems the place where you looked that up is not up-to-date. We
got a couple of PH exclusive mega evolutions during the last advent
calendar event. In case you were wondering, the pokemon besides
luxray that got mega evolutions are milotic, flygon, and claydol.
(Additionally, froslass has had a mega evolution on PH for some
time longer.)