as a man who ran sun my entire gen 8 ou career (tail end of the gen) I feel like I can give suggestions.
Firstly, a lot of people in the comments are right. Ninetales is completely outclassed by Torkoal. Torkoal has better bulk (monstrous def stat of 140) which it can also use offensively via Body Press. it also provides switchin opportunities for your other mons via Yawn or maybe Will-o-Wisp, along with Rapid Spin support for your numerous Stealth Rock weak mons (why is nothing running heavy duty boots), and it can provide Stealth Rock of its own for chip, although I have experimented ditching it for dual status. Also, that Ninetales is flash fire, so this literally isnt a sun team anymore, just fire spam with more fire types I ever ran on one team (gen 8 nd with 3 is my record) go with Drought Torkoal with Heat Rock, then you'll have 8 turns of sun that can let your fire mons wreak havoc.
Next, Roserade is...odd. I never used it in my life, but I can tell you have some inconsistencies with your information. Energy ball is not powered up by sun; in fact, no grass moves are. the only "buffs" they get are solar beam and blade getting no charge (correct me if theres more grass moves buffed in sun). Sun only gives boosts to fire moves (and hydro steam, but screw wake) I feel like Rose has no place in the gen 8 meta. If you want a fast spiker, go with, idrk, Mew, at least it can provide pivot support along with an endless movepool (obv mew is no speedster but is the best fit). if you do insist on using rose, either go full in with 4 atks or 3 atks and synthesis, or full defensive with Black Sludge and defensive EVs. I do not recommend either, though, as most of the time Venusaur just does everything.
Ah, zard. I spammed the living daylights of it to decent success. let's just put it simply: zard's biggest problems in the general ou meta is its meh speed and ok spa. its spa is already remedied by solar power, so how do we fix the speed issue? Sticky Web doesn't synergize well with sun (you need to have a sun setter AND a webs setter, tbh too much) and Tailwind sucks, so naturally, you would run scarf, right? But isn't scarf too restricting? nah it 2hkos mons like pult on the switch with fire blast/weather ball, you'll be fine just spamming the move. As for the set, strong fire move is a must. This isn't gen 5; sun isnt permanent, and you have to make the most of it before having to switch torkoal back in, so screw fire spin. I prefer the nuclear power of fire blast, but weather ball can be nice for accuracy, while also chunking Pelipper trying to reset the weather with a rain boosted move. Scorching Sands/Focus Blast is also a must, you need a way of getting past pex/ttar/friends, however I never tried running both on one set. This is because I often use Solar Beam (obvious) and Dragon Pulse (to ohko unsuspecting dragons). However, if you are more concerned about longevity, a bulkier set with Heavy Duty Boots, Roost, Flamethrower, and slightly defensive EVs can also be used, although that's not the vibe I'm getting off your team. Also, to explain why fire spin is bad: if you switch zard in, you want to trap mons with a bad matchup. However, most mons with an ok to good matchup will mostly stay in, and even if, say, a grass type switches out, it will usually to be a resist or something and the spin will do minimal damage while that switchin will probably force you out, causing you to lose momentum.
Venusaur is a great pick, and the only problems I see are EV spread and movepool. First of all, a b u s e c h l o r o p h y l l. Chloro is what makes sun, sun: Strong fire mons backed by fast grass types to fight against waters. Get maximum speed and special attack, and go with Modest; chloro is broken anyways. As for moveset, Growth allows a swords dance and nasty plot on the same turn, assuming you are under sun. Do not run Solar Beam, as it will be rendered useless outside of sun (the reason zard runs it is due to a lack of grass coverage). Instead, use Giga Drain or Energy Ball, depending on if you want regen or power. Throw on Sludge Bomb for dual stab, or Earth Power to destroy Heatran (EP is probably the better choice). As for the last move, Weather Ball works just fine. Do not use Leftovers, as it is completely outclassed by Black Sludge on poison types. If a non-poison type tricks away Leftovers, they themselves will be using it, however Black Sludge will instead damage them every turn.
For Chandelure, just use Blacephelon. Mystical Fire is a total waste of time due to your team's fast playstyle, and Hypnosis is too hella unreliable. Chandelure does have strengths. It can run a brutal Choice Scarf set to barrage the opponent with its STABS, even able to trick away its scarf onto defensive walls. It can run a Substitute - Calm Mind set to set up on defensive mons. The problem is Blace does all these things better. Higher speed means it doesn't rely on scarf, higher spa means more ohko potential, it even has Psyshock to blow past Toxapex and Blissey. The only downside is that it lacks grass coverage, however I don't think that's a concern of yours, considering your current Chandelure set. Blace is also frailer, but as mentioned before, sun is an offensive playstyle that necessitates strong attackers, and doesn't focus much on defense. Thus, just use Blace. It's one helluva clown to use, I'll tell you that.
Finally, for Talon...look below.
Sun has a lot more options that just fire and grass types; it can synergize well with many other Pokemon. The team I used in the 1500 area is Torkoal, Charizard, and Venusaur, accompanied by Weavile, Garchomp, and Regieleki. Choice Band Weavile is a great wallbreaker, Leftovers Garchomp with Swords Dance and Scale Shot for setup can end games without needing sun, and a peculiar choice in Boots Regieleki can act as a second hazard clearer, while acting as a pivot, while threatening Pelipper. Other potential options include Volcarona, a powerful winged moth that has been a sun stable throughout the generations (literally), Victini, for immense wallbreaking power, Landorus-T, a pivot that can stablilize the team's defense should that be necessary, Tapu Koko, a Pokemon I find synergizing incredibly well with fire types, and if you run Koko, Hawlucha can patch up sun teams' speed issues they often find themselves in when outside of sun. Replace Talon and probably Rose as well with two of these mons, and you'll be good to go!
Also, reference smogon.com. They got some great movesets and probably deeper analyses than anything I can muster. I'll also link my team if you want a reference for a mid ladder sun team.
https://pokepast.es/c10e831d5d4b05f5
Note: I have learned a lot more about the meta since I published this pokepaste (about when gen 9 started), and so some parts are outdated. I recommend Yawn over Plume on Torkoal and Growth over Bomb on Venusaur, but other than that, the team is up to date.
Hope this helps, and good luck climbing ladder!
