Yes, but I think Haxorus is a fair argument as while it's a sweeper, it's also a breaker as well due to SD. It does need a turn of set-up, but once it does it's harder to force it to switch out because of it's speed boost with scale shot and nigh perfect coverage available (namely poison jab and CC) and base 147 attack + Mold Breaker to beat the Unaware mons, and it's sitting in C- right now. I'd like to see you address this
Haxorus's biggest problem when compared to drago is that it really needs that turn of set up to threaten mons like corv, tangrowth, fini or celesteela and can't just be teleported/u-turned in front of defensive mons to do so because you won't be able to OHKO them without boosts and they can easily cripple you if you just set up in front of them, whereas regidrago immediately puts in OHKO pressure and doesn't really care too much about the things the ones that aren't ohkoed could do to it anyways (tran can't hit it hard enough to not lose the 1v1, same for corv or ferro, even if they are sent out full and not on the switch, although u have to watch out for twave ferro).
The problem with Regidrago is that you are investing in a pokemon that is a slow (base 100 beats some breakers but is not useful to rely on) wallbreaker that needs pivoting but completely fails against more than half of OU teams.
How does it fail against half of OU teams though ? Even when having an immunity to it, you're forced into a 50/50 everytime it comes out, with the drago player being at advantage because they have the offensive momentum. Letting in a melm or nido on the double could cost you a lot, just as much as staying in, when Drago doesn't really mind firing a dud and being forced out too much (and it could even stay and click energy again if you predict them to double back out).
Outside of theoryplay concerns like these which I have already went into great length about, I provided several replays where drago provided pressure and value against teams that did have a fairy. For example,
here, (yes my opp is playing a bad team but that doesn't really matter in the point I'm trying to make), on turn 15 my opp doesn't go to their fairy on dragon energy, predicting me to double to tran to catch gardevoir, which would put them in a bad spot, so they have to try and predict it. At the same time, making the wrong predict (like they did) also costs them a lot, while for me, having garde block energy doesn't really matter, because my team is built to handle fairies well, so I'm just free to click anyways and just lose a bit of momentum in the worst case scenario.
So yes, it's worse against teams with fairies than against teams that don't but 1) it's fantastic in that scenario (which, as you said yourself, is about half the time), 2) it's by no mean "useless".
it being slow, choice locked, and needing pivots relegates it to balance and some BO's and those team styles cannot afford to have a slow breaker that usually fails. those teams instead like to have one or possibly 2 (2nd one faster) breakers they bring in with pivoting over and over again and then having a cleaner and/or speed control to finish the team off. in that model, regidrago doesn't fit because it fails against too many teams instead of being a generally reliable breaker such as Lele, Volcanion, and Weavile that work against most if not all defensive cores.
But exactly what breaker has the ability to break effectively versus entire teams alone, except something like Lele (which is A rank rn and thus shouldn't be used as a point of comparison) ? Even volcanion and weavile appreciate support, and it's rare to run only a single breaker, just to avoid losing versus fatter teams if they happen to have a perfect counter, or to have a backup in case it goes down. When put in tandem with another breaker in an offensive core like drago + melm, drago + nidoking, drago + mbeam nihilego, etc... it can do exactly those things you mention, coming in on every defensive play to create another opportunity for you.
Zeraora works because there are a good amount of tools to force damage onto ground types such as aqua tail garchomp and air balloon heatran and it carries knock, but Regidrago has fewer tools to force damage on fairies as some are purely offensive and others do not share mons that reliably force damage on them.
Hazards, magma tran, having several toxicers/statusers on the team, are all tools that are available to force damage onto fairies and that aren't purely offensive, while also being pretty splashable. Besides, in a game where the threat of drago forces your opponent to play conservatively with their fairies and thus not use them to check your other threats, even if you did not force damage on fairies, chances are you're in an advantageous position because of Drago anyways.
There's quite a few reasons why volcanion is better than regidrago, I wouldn't compare them, even by their defensive aspects. I would argue regidrago is actually weaker to rocks than volcanion is because you are making your dragon energy much weaker even after 2 rounds of rocks and no other hazards, whereas volcanion will be just as strong at 100% or at 1%. This makes it MUCH less dependent on specific support like teleport, slow u-turns, hazard removal etc. The calcs you posted with specs dragon energy are very impressive, but at 75% health you cannot even reliably 2hko corviknight ( (48.6 - 57.1%) -- 46.9% chance to 2HKO after Leftovers recovery). Volcanion and regidrago absolutely don't suffer from the same chip issues. Volcanion is fantastic and consistent because it has some defensive utility with water/fire typing and water absorb, and doesn't require slow pivots+ (>80%) health to function.
Almost completely agree with this part, but I feel like volc still becomes much worse if rocks are up (and it's specs), as trying to switch it in hard immediately becomes way riskier and thus it makes it harder for you to keep the pressure up wit hit. Because it has a similar speed to regidrago, even though it has a better typing and good defensive ability, it also doesn't really switch in that much easier than Drago; apart from choice locked water or 4x resisted fire moves, you still hate switching into anything because that chip will accumulate, and everytime you have to switch it back out it will be come harder to bring it in again as you'll be at risk of being 2HKOed by what you're trying to switch into. So I feel like u-turn/port is definitely also really great, if not necessary, for specs volc.
Besides, even if for example corv becomes able to switch in semi-reliably when drago gets lower, it will still have to spend that next turn roosting because else it won't be able to switch in next time, which is a turn you can easily exploit to keep the pressure up with another mon; so it remains difficult to switch into, even at lower percentages, especially when you consider the fact that just specs
pulse from drago is STILL about
just as strong as anything that specs volc can throw out, even though it's more unfortunately typed :
252+ SpA Choice Specs Dragon's Maw Regidrago Dragon Pulse vs. 248 HP / 8 SpD Eviolite Chansey: 181-214 (25.7 - 30.4%)
252+ SpA Choice Specs Volcanion Steam Eruption vs. 248 HP / 8 SpD Eviolite Chansey: 187-222 (26.6 - 31.5%)
Because of all this, I do feel like volcanion, while being overall more reliable (mostly because of the fairy "situation"), suffers from VERY SIMILAR issues to drago, so it's unfair to act like those are traits that prevent a breaker from being good, or even just usable, as volc demonstrate.
The last sentence is wrong but also irrelevant, every mon has its checks, and specs volcanion under rain will blow away pex/gking with steam eruption, even ignoring specs earth power.
Yeah, every mon has its checks, so what's wrong with drago having its own ? It has 5 defensive checks in the tier (6 if you count bulu), but everything else falls to it, and it's able to create opportunity by reliably forcing in those checks. Rain is also additional support required for volc to break through pex and gking. Similarly, if you add another layer of support to regidrago in the form of doom desire jirachi or even just an fsight slowtwin, it also becomes much much harder to switch into, even for fairies. (Specs EP will hit quite hard but no ohko, and considering they have regen and probably a ground immune like every team, in practice it's not that easy to break pex and gking with.)
Regarding whether or not this mon should be ranked, let's compare it to breakers in C-. I think some apt comparisons would be specs solar power zard or band darmanitan. Both require sun, hazard control, and some pivots to bring in, but neither needs to be kept very healthy. I think specs regidrago and specs zard/band darm require similar levels of support. And what are the results of providing so much support? Both of these mons are actually unwallable, not deadweight half the time. There literally isn't a mon under the sun (heh) that can take these two. Regidrago gives significantly worse returns than charizard and darmanitan provided similar support, and I would thus keep it unranked.
I feel like you're pulling at strings here. Specs zard and band darm require to be put on a whole sun team + have one or two VERY reliable hazard remover, so they pretty much lock you into having either mandi or corv as they are the most reliable defoggers which suffer from their own issues when using them on offensive sun teams, so that's really a lot of support, more than drago despite what you may seem to think.
Because they absolutely cannot be used when rocks are up, as they take great damage from them while also chipping themselves very hard with solar power or fblitz, it can be very hard to find an opportunity to actually bring them in, as you need to have both sun up and hazards down for them to be able to do their job, and the only viable sun setter is a passive, slow mons which gets rocked on by everything despite having rapid spin.
They also have a meh speedtier and absolutely NONEXISTANT defensive utility, on top of being very predictable and suddenly becoming much harder to use once tran enters the equation.
Moreover, playing sun puts you at risk of losing to every other weather super easily because it's extremely hard to keep bringing in torkoal vs sand or rain, and even hail can take advantage of torkoal's abysmal speed to just put on pressure with arctozolt, even when hail is down, similarly to how playing drago comes with the price of having a harder time against teams with fairies (but sun vs other weather is even worse than that).
With all that in mind, I feel like your last sentence is kinda preposterous, unless you happen to be the best sun player in the world and can make every prediction right while also being able to keep rocks off and sun up at all times while still not letting pressure go so you don't risk switching darm or charizard on any move that might bop them (which is almost every move in the game). Regidrago definitely needs considerably less support, and puts out better results on average. To me they shouldn't even be ranked, eruption tran and band victini are infinitely better sun breakers.
Yeah specs regidrago's dpulse and draco are certainly pretty strong but I think the main reason of using it at all is its incredibly strong dragon energy. If we were to ignore dragon energy, I would rather run specs latios. It has a very solid speed tier that can rk kart, more coverage than it can even fit in 4 slots+utility options like trick, and actual defensive utility and doesn't require as much pivots/hazard removal. So for the rest of this post, I'm assuming dragon energy is what you're building around, and the other moves are just accessory.
Pulse is still stronger than any of specs latios' moves, but the rest of the points are extremely valid and latios is probably a better breaker than drago in most cases (hence why, once again, i'm only nomming it to C/C-).
Skipping ahead a bit because anything between that and the next thing I mostly agree with.
It can switch into clefable's moonblast, ferrothorn's leech seed/body press/power whip/etc, lando's toxic or eq, buzzwole's cc/ice punch/toxic, corviknight's body press/brave bird, kartana scarf locked into leaf blade/sacred sword, etc etc. Regidrago can't do any of this, it's fully reliant on pivots to get in cleanly.
In theory yes, but in practice zard is chipped by its own solar power and thus even small hits are something it hates. Besides buzz's cc or ice punch actually deal quite a lot of damage ( 0 Atk Buzzwole Ice Punch vs. 0 HP / 0 Def Charizard: 89-105 (29.9 - 35.3%)), even corv's brave bird probably does like 25-30%, and it hates being toxiced as that just adds even more the the chip of solar power, especially since it needs to be able to stay in for several turns to break some mons (like pex). Drago might not be able to switch into all these moves, but it doesn't mind toxic or burn too much either because it usually only stays in for 1 turn anyways, and being chipped is not as dramatic as you make it out to be as pulse remains threatening to a lot of mons. Yes going below 60% means you are no longer able to break a handful of mons as effectively, but once you broke them, you can play more freely with your regidrago. Similarly to the examples you gave, it switches into bro or pex's scald or on fsight, on seismic tosses due to it having humongous hp, on volcanion's fire blast or steam eruption should the need arise. Zard is also very easily ohkoed by mons like zerora, koko, and generally faster threats even from full, which a healthy drago can stay in on and trade with should the need be.
Zard can revenge kill non scarf lele/urshifu/defensive zapdos, rillaboom etc and ohko them as well, as it should be timid. Regidrago is slower and can't really revenge kill much.
Regidrago can revenge kill volcanion and defensive zapdos as well (which it both outspeeds, because noone is running max hp max speed zap), shifu locked into a water move, or any +1 ultra beast that's not specs/band due to being way bulkier than zard and being able to take 1 hit. This kinda feels like a moot comparison, they just have different things they can rk/trade with...
Overall it's easier to get in, which is very important for a wallbreaker. And remember this is the frail fire/flying mon which loses 1/8 hp every turn, so this is a low standard.
Doesn't seem that way to me, especially with the points I explained above.
So yes, running a dedicated sun team is a lot of support. But zard is less reliant on pivots which regidrago absolutely needs to be worthwhile over smth like specs latios. It's my subjective opinion, but yeah, I think marrying your regidrago to slowbro really isn't much better than needing to run torkoal.
Are you comparing one of the tier's premiers defensive pivot, with decent pressure options in fsight, ice beam for chomp and landot, scald to burn anything, reliable recovery + the amazing regenerator to the chippable, walking liability waiting to be set-up on,
FIRE-TYPED DEFENSIVE POKEMON that torkoal is rn ? Bro is amazing, and it's undiscutably better to run bro on every team than torkoal.
That last part you mention is "partners like melmetal, heatran, and nidoking" just reads to me like "My wallbreaker needs other wallbreakers to break walls before I can start wallbreaking."
Again, most teams like to run two breakers anyways, so I don't see how that's much of a problem, and defensive tran is great with drago all the same.
So yeah, I really feel like that comparison was kinda wonky and Drago is definitely better, easier to use/bring in and requires less support than specs zard overall.