>>18125476>Sylveon is meant to be a special wall252 SpA Life Orb Greninja Hydro Pump vs. 252 HP / 0 SpD Sylveon: 160-188 (40.6 - 47.7%) -- guaranteed 3HKO after Leftovers recovery
Greninja is by far the most common special attacker in OU (that's used as full on special attacker, Rotom-W and Heatran don't count.) You use defensive Sylveon for exactly the same reason you use specially defensive Hippowdon: Sylveon's base special defense is so high that it can counter the majority of special attackers without investment in it, while investing in its defense allows it to counter/check phsyical attackers it otherwise couldn't.
252 Atk Garchomp Earthquake vs. 252 HP / 0 Def Sylveon: 232-274 (58.8 - 69.5%)
252 Atk Garchomp Earthquake vs. 252 HP / 252+ Def Sylveon: 154-183 (39 - 46.4%)
