>>23219099Altaria has the versatility to simply adapt to Aegislash's presence. Would it still be S rank? No, mostly like not, because Aegislash would shake up the entire meta. Would it drop to UU like your retarded hate boner wants? Not a chance. It's way too good to drop, especially when Altaria can still break past it with its current sets provided you don't play like an idiot.
252 Atk Mega Altaria Earthquake vs. 252 HP / 0 Def Aegislash-Shield: 136-162 (41.9 - 50%) -- guaranteed 3HKO after Leftovers recovery
+1 252 Atk Mega Altaria Earthquake vs. 252 HP / 0 Def Aegislash-Shield: 204-242 (62.9 - 74.6%) -- guaranteed 2HKO after Leftovers recovery
252+ SpA Mega Altaria Fire Blast vs. 252 HP / 4 SpD Aegislash-Shield: 164-194 (50.6 - 59.8%) -- 85.9% chance to 2HKO after Leftovers recovery
This is different to the likes of Mega Gardevoir and Mega Heracross, both of which have to carry Shadow Ball and Earthquake, respectively, otherwise Aegislash just completely shut them down. They don't need nor use those moves outside of Aegislash, whereas Altaria already uses Earthquake and Fire Blast on its sets.