More of my thoughts on Combusken:
I see much similarity between Combusken and Shuckle; both are very consistent at their jobs, and their support extends to the whole team. Both have good enough bulk to perform their job more than once throughout the match and also allows them to set up easily, generally making it harder to stop them than it is for them to get going. Both Pokemon also promote a form of formulaic teambuilding: Shuckle wants spinblockers and Defog-deterrents as teammates, while Combusken partners usually have a phasing move immunity; considering these partners also benefit from the suspects' support, this makes it so that it can be very difficult to stop them with just one method. While both Pokemon are by no means broken by their lonesome, their consistent and universal supporting capabilities put them a notch above their respective tier.
The Combusken set that is all the rage at the moment is the Bulk Up set, taking advantage of the slightly bulkier meta after Sigilyph's departure. Its typing and Eviolited bulk allow it to setup on a large majority of defensive Pokemon, and occasionally even common offensive ones such as Shiftry, Spiritomb, special Sceptile, and Choice-locked Typhlosion. While I don't doubt that defensive teams will be able to come back from this, it is still likely to shift the meta toward a more offensive direction, and this is where Combusken's other most dangerous trait, aside from consistency, lies: versatility. An offensive meta makes for a frailer metagame, but Combusken has Speed Boost to take advantage of that. While the Bulk Up set has a trickier time setting up against offense, all the flaming chicken has to do is switch to a fast offensive spread with Swords Dance or just "dual STAB Blasts" (special Combusken) to give offense a good run for its money, while still maintaining its Passing prowess. So with its sets threatening both defensive and offensive teams, and even the ability to attack physically or specially, almost any team facing Combusken needs to correctly predict Combusken's set (not easy considering the general similarity of each set's teammates), lest they make a crucial misstep and be too far behind to stop Combusken.
This is not to say Combusken does not have its responses. Haze is usually the best way to stop Combusken from going crazy, since phasing moves can be blocked by passing to immune teammates (Xatu for undamaging phasing, Ghost for Circle Throw, Fairy for Dragon Tail, Steel for Clear Smog; Substitute blocks the last three by itself, while Suction Cups Pokemon stop the former 4 @3@). Even then, due to Combusken's strong offensive capabilities, only a few Haze users can safely stand up to all Combusken sets, namely Qwilfish, Dragalge, Mantine, Lampent, and Dusclops / Dusknoir. Even though these Haze users can stop Combusken well, incorporating Haze into their movesets can be a huge opportunity cost, as it either takes up valuable coverage, consistency, or a niche that can be fulfilled by few other Pokemon. An example for the list of options you don't want to drop would be, for Qwilfish (Spikes, Thunder Wave, Pain Split, Toxic Spikes, Taunt, Poison Jab), Dragalge (Choice Specs, coverage, Toxic Spikes, Dragon Tail, one of its STABs), Mantine (Defog, RestTalk, Air Slash, Toxic), Lampent (coverage, Will-o-Wisp, Pain Split), and Dusclops/Dusknoir (...Spiritomb lol). Considering the relative uselessness of Haze compared to their other options, one can see the 'forced' use of Haze to stop one threat as overcentralisation. Perish Song is an option, but not only does it have a slower effect than Haze, the only Perish Song users that can fend off Combusken are Politoed and Altaria, both of which already have Haze >_> and you generally don't want to use these over other alternatives. Prankster Encore can prevent Combusken from passing any boosts...the only problem being that none of the Pranskter Pokemon can actually switch into an attack.
Conclusion: Aside from its well known consistency, its ability to adapt to the meta with ease while threatening a lot of team archetypes, and the difficulty / impracticality of stopping it has, in my opinion, pushed Combusken just a tad far.