Just calculated some bulky defensive pokes taking a hit against mega salamance. The calculator I used:
http://honko.byethost8.com/APC/ap_calc.html
252+ Atk Aerilate Salamence Return vs. 252 HP / 88 Def Ferrothorn: 192-226 (54.5 - 64.2%) -- guaranteed 2HKO
252+ Atk Aerilate Salamence Double-Edge vs. 252 HP / 88 Def Ferrothorn: 223-264 (63.3 - 75%) -- guaranteed
Would you look at that, OU's right hand man for physical defence and support folds to Sega Salamence's power. Sure, you'll live one hit and be able to maybe get your rocks off or maybe even a leech seed to make the return be a 3HKO (if you get minimum damage on the return the next turn). But if that mega salamence has 1 dragon dance up, It's a definite 2HKO: +1 252+ Atk Aerilate Salamence Return vs. 252 HP / 88 Def Ferrothorn: 286-337 (81.2 - 95.7%) -- guaranteed 2HKO. (Calculated this with salamence's base attack changed to 145 because that's the mega's base attack stat and with an adamant nature and with the mega's ability, Aerilate). One last thing: +1 252+ Atk Aerilate Salamence Return vs. 252 HP / 88 Def Ferrothorn on a critical hit: 429-505 (121.8 - 143.4%) -- guaranteed OHKO. But of course, this all depends on luck. All the same applies to double edge but it will be a definite 2HKO regardless of leech seed. And, you would still OHKO if you get a crit.
Your up, mega Slowbro! As oppose to Ferrothorn, which has base 131 defence, mega slowbro has base 181. Let's see if it will can stop the savage beast.
252+ Atk Aerilate Salamence Return vs. 252 HP / 252+ Def Slowbro: 121-144 (30.7 - 36.5%) -- 62.7% chance to 3HKO
252+ Atk Aerilate Salamence Double-Edge vs. 252 HP / 252 Def Slowbro: 156-184 (36 - 41.6%) -- guaranteed 3HKO
Well... I think we just found a check to mega salamence. Not to mention, look at this:
4 SpA Slowbro Ice Beam vs. 0 HP / 4 SpD Salamence: 312-368 (94.2 - 111.1%) -- 62.5% chance to OHKO
Hmm... maybe this beast is stoppable? Oh, I forgot! Sub dragon dance is a thing on this poke. So if you play it right, you could take out the Slowbro. Maybe set up a sub before Slowbro comes out then do a dragon dance. Because after 1 dragon dance, this happens:
+1 252+ Atk Aerilate Salamence Return vs. 252 HP / 252+ Def Slowbro: 181-214 (45.9 - 54.3%) -- 53.1% chance to 2HKO/+1 252+ Atk Aerilate Salamence Double-Edge vs. 252 HP / 252+ Def Slowbro: 211-250 (53.5 - 63.4%) -- guaranteed 2HKO. Hmm.. that doesn't really make a difference. Let's try an outrage.
252+ Atk Salamence Outrage vs. 252 HP / 252+ Def Slowbro: 109-129 (27.6 - 32.7%) -- guaranteed 4HKO
+1 252+ Atk Salamence Outrage vs. 252 HP / 252+ Def Slowbro: 163-193 (41.3 - 48.9%) -- guaranteed 3HKO
Sigh... In that case, just switch your Salamence out... If you can't then good game. But, if you get a +1 double edge off and hit mega Slowbro on the turn it comes in, that could solve the problem of mega Slowbro.
But nevertheless, the ORAS metagame is still in it's infancy. I mean, the game just came out yesterday for North America lol. Maybe someone will find a check or maybe even a counter to Mega Salamence.