I always wish I'd actually bothered to use it when playing RSE for the first time haha, it's really cool but I've never actually tried it out. Perhaps next time I replay the games. But yeah I agree Shedinja is awesome! :)
Shedinja and Ninjas are the two I've never found space for in my team. I'm actually raising a Shedinja now in my Emerald post-game because I believe it's the perfect pokémon for capturing legendaries, provided you evolve it at lv. 25 or higher to get False Swipe. As it is only weak to Fire, Rock, Ghost, Dark and Flying all of the following can't touch it in my Gen III/IV / V games:
Emerald: Latias / Latios, Kyogre
Diamond: Mesprit, Azelf, Uxie, Rotom, Cresselia, Regigigas.
Platinum: Mesprit, Azelf, Uxie, Rotom, Cresselia, Regice, Registeel, Regigigas, Dialga, Palkia, Articuno, Zapdos.
HeartGold: Raikou, Suicune, Mewtwo, Kyogre, Latios.
Black: Cobalion, Virizion, Kyurem.
Black 2: Cobalion, Virizion, Terrakion, Zekrom, Kyurem, Latios, Mesprit, Azelf, Uxie, Regirock, Registeel, Cresselia.
Considering how time-consuming and expensive (in terms of Revives, Hyper Potions / Full Restores as well as Pokéballs and having to raise your pokémon to a high level) capturing a legendary is, Shedinja may well be one of the greatest pokémon of all time