I don't see how any variant of Lucario could possibly sweep through this team. Hippowdon survives a Jolly +2 Close Combat and KOs back with Earthquake. Gyarados does an excellent job of countering any set, and Lucario won't survive repeated LO recoil and switch-ins into entry hazards. Scarf Tyranitar can easily revenge kill sets that don't run Bullet Punch, which is often the case. I feel that a lot of the "major threats" that people are pointing out can be attributed more accurately to their own misplays than to the team itself.
Jolly +2 LO Close Combat vs 252/4 Hippowdon: 93.1% - 110%
1HKO'd after SR. Did you even read the EVs? This Hippowdon is all specially invested. It's not your normal Hippowdon
Scarf Tyranitar does revenge, but I've had occasions where Lucario runs SD/Crunch/Bullet Punch/CC (which is actually viable because Extremespeed doesn't hit Gengar). Which can suck.
^
+1 Breloom Seed Bomb vs 248/252+ Gyarados - 59.5% - 70.2%
+1 Breloom Mach Punch vs 248/252+ Gyarados - 15% - 17.6%
More often than not Rocks are spun meaning you'll never ko gyara unless it switches in on a +1 seed bomb already or has signifigant prior damage.
Stone Edge is pointless because if Breloom has stone edge then it lacks seed bomb, so Rotom walls it 100%. 4 moveslot syndrome, the way this team beats most threats also beats SD Breloom.
It's not a completely unlikely scenario that rocks are spun away, Gyarados has taken a previous beating, or his sleep talk doesn't select Roar and he gets 2HKO'd. Not to mention after taking that minimum 60%, Gyarados roars and ends up being crippled without even killing Breloom.
I'm not stating this team isn't near perfect, because it is, but I'm just stating the flaws of the team, which is that Gyarados might be overwhelmed with physical threats sometimes. I've considered changing Hippowdon's EVs
Also another nitpicky problem that I've found is bulky SD roost Scizor. You're going to think I'm crazy, but without a fire attack, this Scizor eventually becomes the last pokemon and gets +6 because nothing can do enough damage to beat his Roost. The only way I've found beating this Scizor possible is hoping Rotom-H is still alive at the end and using Thunderbolt to paralyze it so it can be killed within a full paralysis.
Let me reiterate though, this team is still
practically perfect. It is an amazing team, really.