In Pokebank I run Return / PUP / Fire Punch / Sucker Punch. This lets you kill Skarmory after a boost and Ferrothorn right away, plus gives you something to hit non-mega Gengar with when he uses sub. The only downside to using fire punch over EQ is that king's shield can lower your attack if you use fire punch at the same time as it, but you can get around this with sucker punch. Sucker punch doesn't activate the attack loss at the same time as king's shield, so if you predict correctly you can still get around Aegislash. IMO it's definitely worth it to be able to take out Skarmory and regular Gengar (who, without fire punch, are the only safe switch ins I can think of).
Anyway, there's no way this long lasts long in OU. It can come in on anything except faster fighting types, a full health Aegislash, or pokes with will-o-wisp, then proceed to kill something. Walls that can take a return but can't deal much damage in return are setup bait, and that absurdly powerful sucker punch is just icing on the cake. With parental bond and the base attack from mega form (125) counted in, that sucker punch is stronger than extreme killer Arceus's extremespeed, plus it breaks substitutes. So yeah, enjoy this thing in OU while you can.