First off, like all hacks and glitches, this action may mess up your game.
To answer your question, it will be able to block from moves like pursuit, but not from something like a damaging status problem or moves like cross poison, which can cause poison. I would not see this working towards the fact that sandstorm/hail, confusion, poison/burn, and entry hazards will KO shedinja, in similarly to shedinja's actual ability wonder guard.