A large part of why blaziken isn't considered broken is not just its frailty, but that it isn't always able to accomplish much due to the pick your poison nature of choosing z move coverage, which necessitates prior setup to not get cleaved open by a revenge killer. It also struggles with numerous bulky waters and grounds due to the reduced power of its coverage or stabs without life orb. Enter Drought. The 1.5x boost to its fire stab and halved damage from water attacks allows blaziken to setup much more easily vs many threats and not get walled in turn. For example, it turns tapu fini from a check to setup fodder by halving the damage from scald and boosting Firium z to staggering levels of power. Here is just a sample of what it can do:
+2 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 4 Def Latias-Mega in Sun: 411-483 (112.9 - 132.6%) -- guaranteed OHKO
+2 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 252+ Def Slowbro in Sun: 325-383 (82.4 - 97.2%) -- 62.5% chance to OHKO after Stealth Rock
+2 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 0 Def Toxapex in Sun: 335-394 (110.1 - 129.6%) -- guaranteed OHKO
+2 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 252+ Def Toxapex in Sun: 258-303 (84.8 - 99.6%) -- 81.3% chance to OHKO after Stealth Rock
+2 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 148+ Def Kommo-o in Sun: 321-378 (90.6 - 106.7%) -- 81.3% chance to OHKO after Stealth Rock
+1 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 252+ Def Landorus-Therian in Sun: 559-658 (146.3 - 172.2%) -- guaranteed OHKO
+2 252+ Atk Blaziken Inferno Overdrive (190 BP) vs. 252 HP / 192+ Def Tapu Fini in Sun: 330-389 (95.9 - 113%) -- 75% chance to OHKO
I could go on but you probably get the point. Nothing walls this thing under sun barring water type unaware pokemon on stall teams, who still take nearly 50% from close combat and have a slight tendency to let their stall teams get 6-0ed by venusaur. Pelipper is also an issue due to resisting both stabs and changing the weather, but sun teams usually have the tools to beat rain teams regardless, so this isn't too much of a problem.
(Note: Any set with firium z paired with drought will have similar calcs, but protect is partially to demonstrate the lack of need for coverage due to the sheer power of z flare blitz under sun. It also has other benefits like allowing it to quasi-automatically outspeed threats as fast as weavile (aka most offensive pokemon in the tier, even unevolved greninja), blocking fake out from medicham and lopunny, and providing the one extra speed boost needed for some scarfers like lando-t.)
Now for the defensive aspect. In addition to setting up on usual targets such as blissey, ferrothorn, tyranitar, heatran switching out, choice locked kartana, etc., it can also set up on tapu fini and toxapex and inflict a massive amount of damage. Even slowbro fails to do enough damage turn 1, allowing blaziken to SD up and send it to the shadow realm with minimal chip.
Torkoal provides sun support (and can hold heat rock for extra sun turns), sets stealth rock with a level of consistency (threatening corviknight, kartana, lando-t, and zapdos with either a super effective burn or status, even threatening stuff like pelipper and fini on a reasonable prediction), and has a significant amount of defensive utility due to it's skarmory-rivaling physical bulk and only 2x weakness to stealth rock. The most obvious point of comparison would be Mega Charizard Y, who has an immense offensive presence, roost, and the ability to threaten rain teams immediately with its coverage. The difference here is that torkoal has a slightly reduced need for urgent hazard removal, has increased ability to pivot in due to its bulk, can hold heat rock for increased sun duration, frees up a moveslot for stealth rock, and can more consistently threaten sand teams with body press rather than relying upon focus blast accuracy. Additionally, it can free up a potential mega slot if one desires to use a different mega. There is an arguement for both setters, but in my opinion torkoal is a better overall partner for blaziken due to its support capabilities.
The exact set provided can have one of toxic or body press swapped out for rapid spin, but each increases the difficulty of the matchup vs rain or sand respectively. Torkoal is also terrible at hazard removal anyway, only threatening ferrothorn who is easily dealt with for this teamstyle. Unlike in OU, it can't even threaten all of the viable spikers, since greninja dominates it. Sun team always need a separate form of hazard removal anyway, so this isn't much of a sacrifice.
Before Blaziken was introduced, sun teams have had a rough time in national dex due to their shaky matchup vs much of the meta. With the addition of blaziken for a fast, flexible offensive sweeper and wallbreaker to compress offensive roles, this might be able to allow them to shore up their defensive backbone or diversify the potential offensive pokemon that could be added.
I submitted this core to this thread
at the end of June, where I am happy to say Torkoal won the vote for best Blaziken partner.