>>29630183I'm going to be boring here, but I think that it's probably a completely amorphous shadow-blob with no discernible features, not even the eyes since they're black except when attacking. The limbs are probably 'created' out of shadow material when they're needed and dissolved after that.
It would also explain why nobody knew they existed until they started mimicking Pikachu, despite them apparently living around humans for a long time.
