tired so thoughts are a little jumbled
sun would prolly still be bad w/ tort. it's not really the inducer causing sun problems, it's more that it simply doesn't compete with rain, which has a wider variety of better abusers, or even sand. swift swimmers > chloro mons, sr weak fire-types = sac momentum to defog, primary hard hitters beat ttar > lose to ttar, greater diversity of abusers...rain still seems loads better.
protean starmie is whatever, i mean stab ice beam is nice but still psyshock + hydro which hit harder given analytic. and then there's greninja which can't spin but is otherwise basically better.
unaware cobalion wont be good because its easy as hell to actually deal with defensively and offensively, and cant recover at all besides lefties. basically too easily checked/countered and overwhelmed. i guess it has sr.
maybe skunk is decent, i mean it has some decent offensive presence with like sucker punch, pursuit, and fire blast in conjunction with defog. out of these it's the only one that will actually have an effect on the meta/really be used.
Crappy sun inducer is easily one of sun's biggest problems. It's just so hard justifying the use of a sun team when Ninetales is such a shitty and restricting Pokemon that is so easy to play around. Hell, as long as you keep SR up you have already handicapped sun teams with Ninetales for the rest of the game. Torterra provides actual defensive synergy and helps with some of sun's problems (Ground-types), has recovery to outlast opposing weather inducers, has SR to support its team, and STAB EQ and Stone Edge to threaten many of the Pokemon that would give to sun teams troubles, such as Talonflame, Heatran, Mega Charizard X, and Mega Charizard Y.
And with your sun inducer not weak to SR, you don't have to stack SR weak Pokemon, just one SR weak Pokemon is fine. Heatran + Mega Doom / Mega Char X is a fine combo, and all of those Fire-types can get past other weather inducers without much trouble (Houndoom with Suny Day as they come in, Mega Char X with DD / SD boosted attacks, Heatran with its Sunny Day + Magma Storm set). Sun teams won't have to use very niche Pokemon with little viability outside of ensuring sun stays up, such as Dugtrio or Gothitelle, as Torterra is way more useful that Ninetales and helps solve many of the problems that sun teams used to have.
Lastly, i don't disagree that rain > sun, but this has always been the case even in 5th gen, and it didn't stop sun from being viable at all. Of course rain didn't have the Swift Swim users back then, but sun didn't have such a great sun inducer, Defog Latios and Latias, Solar Power Heliolisk, Mega Doom, and Mega Char X too. And let's not forget how easily Torterra can switch into the premiere Swfit Swim user on rain teams, Kabutops, while Politoed can't switch into any of the sun sweepers (Mega Doom has Sunny Day, Mega Char X has DD, Heatran has Magma Storm + Sunny Day, Venusaur has Grass STAB, Heliolisk has Electric STAB).
Talking about Heliolisk, his Specs set is really scary under sun. Here are some calcs, assuming a moveset of Thunderbolt / Focus Blast / (Volt Switch / Grass Knot) / Hidden Power Ice:
- 252 SpA Choice Specs Solar Power Heliolisk Hidden Power Ice vs. 4 HP / 0 SpD Latios in Sun: 240-284 (79.4 - 94%) -- 43.8% chance to OHKO after Stealth Rock
- 252 SpA Choice Specs Heliolisk Focus Blast vs. 252 HP / 4 SpD Tyranitar in Sand: 460-544 (113.8 - 134.6%) -- guaranteed OHKO
- 252 SpA Choice Specs Heliolisk Grass Knot (120 BP) vs. 252 HP / 252+ SpD Hippowdon: 306-362 (72.8 - 86.1%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
- 252 SpA Choice Specs Solar Power Heliolisk Focus Blast vs. 252 HP / 4 SpD Eviolite Chansey in Sun: 332-392 (47.1 - 55.6%) -- guaranteed 2HKO after Stealth Rock
- 252 SpA Choice Specs Solar Power Heliolisk Thunderbolt vs. 4 HP / 0 SpD Mega Charizard X in Sun: 167-197 (56 - 66.1%) -- guaranteed 2HKO
- 252 SpA Choice Specs Solar Power Heliolisk Thunderbolt vs. 252 HP / 4 SpD Mega Venusaur in Sun: 124-147 (34 - 40.3%) -- guaranteed 3HKO
- 252 SpA Choice Specs Solar Power Heliolisk Focus Blast vs. 252 HP / 252+ SpD Heatran in Sun: 360-424 (93.2 - 109.8%) -- guaranteed OHKO after Stealth Rock
- 252 SpA Choice Specs Solar Power Heliolisk Focus Blast vs. 252 HP / 0 SpD Ferrothorn in Sun: 458-540 (130.1 - 153.4%) -- guaranteed OHKO
Specs over LO because 10% + 12.5% recoil each turn is too much.