IMO, Glalie is not pretty good in HazardSetting, but very good in Stallbreaking. A simple Set of Double Edge, Earthquake, Taunt and Freeze Dry/Explosion with 252 Atk+/ 4 SpA/ 252 Spe destroys Stall. Status&Co is crippled by Taunt and Skarm, Bro and co...
0 SpA Mega Glalie Freeze-Dry vs. 252 HP / 4 SpD Mega Slowbro: 212-252 (53.8 - 63.9%) -- guaranteed 2HKO
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 252 HP / 252+ Def Skarmory: 151-178 (45.2 - 53.2%) -- 90.6% chance to 2HKO after Stealth Rock and Leftovers recovery
252+ Atk Mega Glalie Earthquake vs. 248 HP / 0 Def Heatran: 432-512 (112.2 - 132.9%) -- guaranteed OHKO
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 4 HP / 252+ Def Eviolite Chansey: 349-412 (54.3 - 64.1%) -- guaranteed 2HKO after Stealth Rock
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 248 HP / 0 Def Charizard: 324-382 (90.2 - 106.4%) -- guaranteed OHKO after Stealth Rock
0 SpA Mega Glalie Freeze-Dry vs. 252 HP / 0 SpD Rotom-W: 168-198 (55.2 - 65.1%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 252 HP / 252+ Def Mega Audino: 162-192 (39.5 - 46.8%) -- 34% chance to 2HKO after Stealth Rock
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 252 HP / 252+ Def Mega Sableye: 163-193 (53.6 - 63.4%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
0 SpA Mega Glalie Freeze-Dry vs. 252 HP / 4 SpD Quagsire: 504-592 (127.9 - 150.2%) -- guaranteed OHKO
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 232 HP / 0 Def Thick Fat Mega Venusaur: 222-264 (61.8 - 73.5%) -- guaranteed 2HKO after Stealth Rock
HO can not switch in safely
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 4 HP / 0 Def Greninja: 183-216 (63.9 - 75.5%) -- guaranteed 2HKO after Stealth Rock
252+ Atk Refrigerate Mega Glalie Double-Edge vs. 0 HP / 0 Def Keldeo: 144-170 (44.5 - 52.6%) -- 82.4% chance to 2HKO after Stealth Rock
There are only a few things that counter this thing, MScizor is probably the best. With SR and Wishsupport, MGlalie is IMO pretty good, even if Mence, Gross and co. are a bit better. And srsly, the Movepool is not THAT bad, Freeze Dry, EQ, Double Edge/Return/Body Slam, Taunt, Explosion and probably Crunch is all you need (ok, Close Combat, Flare Blitz and Shell Smash wouldnt be bad, but srsly). I think MGlalie is going to be a pretty good UU Mega and a good Stallbreaker in OU.