-It was @ Route 16
-Walking on the Normal Grass Patches (Not Dark)
-The Pokemon was a random Gothita or whatever you call it.
-IT WAS NOT SHINY, I was battling that thing so believe me, I know a SHINY when I see one.
-I swear by the only Arceus that the Music was different, I was shocked myself.
All I can say is that it was some sort of Glitch/Bug...