Shedinja depends on the opponents. Make use of its partial invincibility.
My Shedinja is always for defense moves.
It knows attacks like Confuse Ray, Toxic, and just in case, Double Team and Flash.
But even with these attacks active, Shedinja is mune to the following attacks no matter what:
Faint Attack (never misses)
Shadow Punch (never misses)
Aerial Ace (never misses)
Sandstorm (weather)
Hail (weather)
Skill Swap (self-explanatory)