ego

A Shedinja can be really cool, but it has so many weaknesses that it's a real situational Pokémon. Many other know Bite (which itself is a pain in the ass for ghost type trainers) but Shedinja is also weak to fire and flying type moves and not to forget ghost and rock. Most of the time you can't really use it 

You also can't use it against anything that sets up Sandstorm, Hail, Stealth Rocks, Leech Seed, Poison or Burns

RIP spoopy little bug T.T

True there are so many things that could easily kill it :/
Then again: There's no need to put any EVs into Defense and SP.Defense