Since the main distinction between Blaziken and its Mega has been the slightly increased bulk on the mega giving it more space vs offensive teams while limiting it vs defensive teams. I thought id share a few ways I found to deal with Mega Blaziken on offence.
MBlaze hates fighting webs since its starting on the back foot and webs seriously help you deal with MBlaze before it outspeeds all your guys, MBlaze will struggle to find setup opportunities vs anything offensive in this meta if you have webs up and will typically at most get 1 kill then die to recoil or be revenged. If they try and setup 1v1 on Ribombee you have options to stop MBlaze such as skill swap and stun spore.
Apart from the fact MBlaze is easily handled with screens up by any competently built team, if it chooses to SD thinking youll click reflect you can
+2 252+ Atk Grimmsnarl Foul Play vs. 0 HP / 4 Def Blaziken-Mega: 237-280 (78.7 - 93%) -- guaranteed 2HKO
You can also cripple MBlaze with status such as prankster Twave
Rain should have a plethora of ways to deal with MBlaze even without considering all the water priority you can use to handle it.
Thats three of the most common offensive archetypes that all easily handle Mega Blaziken.
I hate validating the people who think ferrothorn fits on an offence, but if ur some chunky BO council mans sample team buildin type this might be for you. Iron barbs + Helmet + recoil/def drop should mean even resisted priority can force blaziken out, and given its a mon that cant setup twice easily this is basically a 1 for 1 trade ensuring you wont get swept.
The best Mega Blaziken counter, Dragonite wit the timbs easily slots into several offensive builds and MBlaze really cant touch you
(or itemless or Z) You can EV a slowbro set to take on MBlaze, just run counter, invest enough spa for scald to ohko or use hydro pump or future sight which ohko uninvested.
+2 252+ Atk Blaziken-Mega Knock Off vs. 252 HP / 252+ Def Slowbro: 246-290 (62.4 - 73.6%) -- guaranteed 2HKO
Tankchomp isnt a check but a way to get some chip using helmet + endure u can guarantee MBlaze gets chipped atleast 50% and is at -1 or -2 to make it removable by even weak priority. +2 252+ Atk Blaziken-Mega Close Combat vs. 252 HP / 240+ Def Garchomp: 378-445 (90 - 105.9%) -- 37.5% chance to OHKO
Calm mind gbro with a mega stone is a brutal wincon vs a lot of teams, you live +2 knock due to the mega stone and OHKO back with psychic, you can also just mega and ohko it wth scald since +2 blitz will kill gbro. Nobody ever expects the mega gbro.
40 SpA Slowbro-Mega Scald vs. 0 HP / 0 SpD Blaziken-Mega: 270-318 (89.7 - 105.6%) -- guaranteed OHKO after Stealth Rock
great cleaner and speed control for offence can outspeed a +2 jolly MBlaze and OHKO
Strong water priority can easily be fit on offensive teams and remove a boosted blaziken with minimal chip
252 SpA Choice Specs Greninja Water Shuriken (15 BP) (3 hits) vs. 0 HP / 0 SpD Blaziken-Mega: 234-276 (77.7 - 91.6%) -- approx. 12.5% chance to OHKO after Stealth Rock
252+ Atk Choice Band Urshifu-Rapid-Strike Aqua Jet vs. 0 HP / 4 Def Blaziken-Mega: 258-306 (85.7 - 101.6%) -- 87.5% chance to OHKO after Stealth Rock
252+ Atk Choice Band Adaptability Crawdaunt Aqua Jet vs. 0 HP / 4 Def Blaziken-Mega: 328-388 (108.9 - 128.9%) -- guaranteed OHKO
Another option to remove a -1 or slighly chipped blaziken (youll find a pattern here just get a bit of chip while its setting up and MBlaze is a non-issue)
252 Atk Aerilate Pinsir-Mega Quick Attack vs. 0 HP / 4 Def Blaziken-Mega: 216-254 (71.7 - 84.3%) -- guaranteed 2HKO after Stealth Rock (But if they click blitz to kill you they guarantee die to recoil so its a trade)
252 Atk Aerilate Pinsir-Mega Quick Attack vs. -1 0 HP / 4 Def Blaziken-Mega: 320-380 (106.3 - 126.2%) -- guaranteed OHKO
Torkoal can eat a +2 Close Combat from full and yawn or toxic or earth power it into range of dying to priority
+2 252+ Atk Blaziken-Mega Close Combat vs. 248 HP / 252+ Def Torkoal: 285-336 (83 - 97.9%) -- guaranteed 2HKO
If sun is up venusaur can switch in to any non fire move and outspeed a +1 MBlaze
252+ SpA Life Orb Venusaur Earth Power vs. 0 HP / 0 SpD Blaziken-Mega: 281-333 (93.3 - 110.6%) -- guaranteed OHKO after Stealth Rock
Mega Lop one of the most ubiquitous HO Mons is great at handling blaziken especially double priority lop which can immediately remove a -1 blaziken if rocks are up or its slightly chipped, also ensures it doesnt sweep you.
252 Atk Lopunny-Mega Fake Out vs. -1 0 HP / 4 Def Blaziken-Mega: 123-145 (40.8 - 48.1%) -- 67.2% chance to 2HKO after Stealth Rock
While this is usually a shaky check due to +2 knock being an ohkoafter rocks, slower pdef reflect type variants can easily adapt to it
+2 252+ Atk Blaziken-Mega Knock Off vs. 252 HP / 100+ Def Latias-Mega: 260-306 (71.4 - 84%) -- guaranteed 2HKO you can also run a mixed bulk max speed set that is a slim roll for ohko with rocks
+2 252+ Atk Blaziken-Mega Knock Off vs. 128 HP / 128+ Def Latias-Mega: 254-300 (76.2 - 90%) -- 18.8% chance to OHKO after Stealth Rock
Unlike regular Z Blaziken, Hippo can actually check Mega Blaziken and ohko with an earthquake
+2 252+ Atk Blaziken-Mega Close Combat vs. 252 HP / 252+ Def Hippowdon: 322-381 (76.6 - 90.7%) -- guaranteed 2HKO after Leftovers recovery
8 Atk Hippowdon Earthquake vs. 0 HP / 4 Def Blaziken-Mega: 288-338 (95.6 - 112.2%) -- guaranteed OHKO after Stealth Rock
Jolly Excadrill in sand outspeeds +2 ada MBlaze and +1 jolly and ohkos.
Cress sets trick room on MBlaze and a lot of TR offences on ladder use sash hat nowadays.
+2 252 Atk Blaziken-Mega Knock Off (97.5 BP) vs. 252 HP / 220+ Def Cresselia: 320-378 (72 - 85.1%) -- guaranteed 2HKO after Stealth Rock
Outspeeds +1 Jolly MBlaze even when modest and OHKOs
252+ SpA Choice Specs Transistor Regieleki Volt Switch vs. 0 HP / 0 SpD Blaziken-Mega: 283-334 (94 - 110.9%) -- guaranteed OHKO after Stealth Rock
Band sets can also revenge a weakenned MBlaze. 252+ Atk Choice Band Regieleki Extreme Speed vs. -1 0 HP / 4 Def Blaziken-Mega: 215-254 (71.4 - 84.3%) -- guaranteed 2HKO
MBlaze cant even guarantee setup on this considering you can predict the SD and 2hko with glide
252+ Atk Choice Band Rillaboom Grassy Glide vs. 0 HP / 4 Def Blaziken-Mega in Grassy Terrain: 142-168 (47.1 - 55.8%) -- guaranteed 2HKO after Stealth Rock and Grassy Terrain recovery
MBlaze is also removed by glide when at -1 and chipped 252+ Atk Choice Band Rillaboom Grassy Glide vs. -1 0 HP / 4 Def Blaziken-Mega in Grassy Terrain: 213-252 (70.7 - 83.7%) -- guaranteed 2HKO after Stealth Rock and Grassy Terrain recovery
While not the most common mon, sash magic guard alakazam can function as an emmergency stop to certain setup sweepers including MBlaziken.
Intimidate salamence switches into MBlaze
+1 252+ Atk Blaziken-Mega Close Combat vs. 0 HP / 0 Def Salamence: 226-267 (68.2 - 80.6%) -- guaranteed 2HKO
252 Atk Salamence Dual Wingbeat (2 hits) vs. 0 HP / 4 Def Blaziken-Mega: 324-384 (107.6 - 127.5%) -- guaranteed OHKO
While its a horrible check to tpunch variants and forces a 70/30 (kinda a 50/50 but a bit in their favor since Tpunch can still roll a mgyara at +1. +1 252+ Atk Blaziken-Mega Thunder Punch vs. 0 HP / 0 Def Gyarados-Mega: 294-346 (88.8 - 104.5%) -- 31.3% chance to OHKO ) you can check knock variants by staying unmega'd
(Unaware only) if you switch in to any attack other than blitz you can spam soft boiled a few times to collect recoil chip then kill with moonblast, wish protect variants may be able to wall it shakily if they dont switch in to blitz.
252+ Atk Blaziken-Mega Flare Blitz vs. 252 HP / 252+ Def Clefable: 220-261 (55.8 - 66.2%) -- guaranteed 2HKO after Leftovers recovery
You can use deo-d as a bulky hazard setter on some offences it eats any MBlaze attack and ohkos back with psychoboost
+2 252 Atk Blaziken-Mega Knock Off (97.5 BP) vs. 252 HP / 240+ Def Deoxys-Defense: 256-302 (84.2 - 99.3%) -- guaranteed 2HKO
12 SpA Deoxys-Defense Psycho Boost vs. 0 HP / 0 SpD Blaziken-Mega: 276-326 (91.6 - 108.3%) -- guaranteed OHKO after Stealth Rock
Other cheese shit like random scarfers and sashers and talonflame can check MBlaze, if you build for it you will find you have so many options.
TL:DR Mega Blaziken has plenty of offensive counterplay available and chip is incredibly easy to get vs a MBlaze (this thing runs flare blitz with low hp ffs) Because of its frail nature u only need to find a way to shutdown a setup MBlaze once in a game which gives you plenty of leeway to use unconventional checks and chip to handle it.