>>33039933In Pokémon, every damage is always rounded so the minimal damage.will always be 1, and Shedinja's Max HP is always 1, so no matter if it is holding a Life Orb, a Black Sludge, using a recoil move on a Pokémon with 1 HP, etc., it WILL always faint from a move or item that involves loss of HP.
If you have a Pokémon game with a Shedinja then turn it on, give it a Life Orb, and try it on Route 2 (XY) or Route 1 (every other games)