If Latios uses Ice Barrier, it becomes immune to everything a Pokémon-ex does through an attack next turn, even if it indirectly affects him (think Ariados's Spider Trap). Therefore, Tyranitar may not place a Shock-wave marker on Latios. The only way it may place a marker is if Latios is forced to the bench (clearing memory) by something like Cyclone Energy or Warp Point.
Edit: Beat me to it, but I won't delete this message. I need the post count. >.>