Ok, so this situation happened during the top cut at my states and I was told during the game that I could not get a ruling for something like this.
Situation:
My Arceus (Metal) with an Omniscient LvX was active and he had in play Gengar LvX.
If I had used Metal Barrier and during the next turn Gengar LvX used Level Down; would my Metal Arceus still be protected from LvX pokemon or does the effect disappear because of the action of Leveling Down?
Edit: thanks for the answer.
As stated, this question asked about the game state after level down and in no way was the use of level down in doubt.