Shedinja is quite a simple Pokémon, design-wise. It's just a shed of skin that Nincada left over when evolving into Ninjask. When it comes to battling, however, Shedinja has gotta be one of the most complex Pokémon that you would ever be able to come across. d: It's got only a single HP, and its overall stats are extremely low. It doesn't have too much of a big movepool, either. It does have an ability known as "Wonder Guard," though, which protects it from any move that it's not super-effective to. Veteran players may have some knowledge on what this Pokémon's weaknesses are and such, but those who are new (most likely) may not, which would give them a hard time when they try to take Shedinja down. Personally, I haven't used this Pokémon in any of my battles, but I might do it at some point in the future!