(Edit: As much as id like a TLDR. There is none. Sunny is a complicated character, and so is playing her right. I largely consider myself a sunny main- even though i tend to refrain from using her in pubs due to her current strength. take it with a grain of salt, but this is my input based on who knows how many hours with this character)
First bit of sunnys kit to understand is her drone.
Upon deployment the drone spawns and begins to charge. it is incapable of shielding anyone after its first deployment until it reaches full charge. The initial charge takes 8 seconds (This is basically its cooldown). From here the drone will target any hunter in range, AFTER they take an instance of damage (It will not pre-shield a hit). The shield drone will then continue to shield that person until A) It runs out of capacity, B) A new target is damages, C) the target it is shielding breaks LoS with the drone, or D) the person its currently targeting, hasnt taken damage in 8 seconds. From here it will de-tether, and begin to charge to full again. The second time the drone begin to charge, it has an accelerated charge rate- and will charge to full in 5 seconds instead of 8 (This is being changed in the next balance patch. The initial, and follow up charges will all be 7 seconds. never understood why it was different, but enh).
The next bit is her jet pack booster- Much like its name implies, it augments the jetpack of the hunter you are tethered too. While “boosted”, a hunter will get increase jet pack velocity/thrust, and instead of using their own jet fuel- WIll instead deplete Sunnys JPB battery.
Her primary weapon is a mini nuke launcher. At one point it was the strongest single shot weapon in the game- It has since been HEAVILY nerfed- Originally doing well over 200 damage, it now does 125.
Sunny benefits BIG time from quick swap and reload perks, in my opinion. Evolve when it boils down to it- Is a damage race. Who can out damage the other side first, is the one that typically wins. Quick swap perks allow you to boost someone away once, get the launcher out, fire a round, and then get back to the booster to continue to boost the hunter- Without the monster ever catching up. It also makes for VERY speed drone replacements should the monster down your drone. Being a single shot weapon, sunnys damage potential over an engagement goes up almost as much as the reload value increase. Ie: 20% faster reload time, is damn near 20% more nukes. Capacity is nice for the JPB, but reload effects both the launcher and the booster- So it works better overall. These perks however do not alter the drone itself. It is what it is, no matter what you have.
First step to sunny is getting the drone in a “good” spot. What is or isnt a good spot, depends on the monster. Against monsters like goliath and behemoth- Typically this is “up high” on a ledge where is has wide LoS over the battlefield. This requires the monsters to use an ability, or spend a traversal, or time climbing to deal with the drone.
For monsters like kraken and gorgon is a bit different. Dont bother putting it up high. Kraken can down the drone with a few snowballs from anywhere in LoS. Instead try to “tuck” it behind geometry. Put it behind a pillar, and make sure your team mates know not to pass “the line” it makes with the pillar so they can have LoS on kraken, but still have LoS on the drone- In a way that doesnt give kraken LoS on the drone himself. Make kraken have to move around to get the drone. Kraken is a solid counter to sunny because of his capacity to down it. The same is true for gorgon, her acid spray is amazingly effective at dealing with the drone. Gorgon can easily, all day, every day, get the drone with the very first part of the acid spray- and then drop the remaining 90% of the sprays ability on the hunter of choice. Wraith due to her mobility is a bit trickier- and she doesnt really have many abilities shell want to use to down it. Instead shell probably blink to it, melee, and blink away. keeping it “out of the way” behind geometry is the best bet here again- making sure to capitalize on it any time you recognize the monster going for it. If you know where the monster is going, you know where to aim to do damage.
Be aware of your positioning in relation to the drone- as well as your teams positioning. If theyre by it, kindly tell them to move the $*@! out of the way and “get over there”. Once you drop a drone down- Do not stay by it yourself. Immediately begin moving to where you want the NEXT drone to be. Once you see the monster starting to destroy your drone- Replace it. Dont even wait until its gone, just replace it. The sooner you replace that drone, the sooner this one will be charged. Repeat the process- Getting into the next area your next drone will be.
The BEST way to use the jetpack booster is PRE-emptively. Not RE-actively. As a defensive support you want to be aware of monster abilities, and their cooldown times. Did a monster just use a big-burst ability? START COUNTING its cooldown. Announce it over mic a couple seconds BEFORE its off cooldown to your team. “ROCK IS ABOUT OFF COOLDOWN WATCH OUT”. Fire nukes until this point, then get the jet pack booster out BEFORE the ability is off cooldown. Beam the hunter the monster is focusing- and hope theyre smart enough to dodge. If youre beaming someone AFTER theyre taking these big hits- Youre beaming them way too late.
That said, it happens. Monsters swap targets, you lose whats going on replacing drones, etc. Sometimes you do have to respond re-actively. This is where quick switch comes in handy. Tier 1+2 swap perks get you 90% reduction on weapon swaps if im recalling the numbers correctly. This drops off nearly a second in swap time. Might not sound like much- But dodging 1 second sooner can often be the difference between a happy hunter, and a hunter taking a dirt nap.
And this is why quick switch is so damn strong on sunny. 1 second may not seem like much- But if you swap gear 20 times in a dome- Thats literally about 20 seconds of time youve saved (Which depending upon the dome- can be a damn conservative number. Swapping from the jet pack booster, to the drone, back to the booster, is 2 swaps afterall). 20 more seconds to be on the launcher. 20 more seconds to be on the booster. 20 more seconds to be dropping drones. The benefit is huge- and i can not recommend that perk enough.
Sunny is an amazingly powerful character- But she does require a degree of coordination. The drones only powerful if the team plays around it. Just because youre boosting someone, doesnt mean they will mitigate the damage. Nor does it mean they will end up in a better spot. I’ve lost count of the amount of times ive boosted someone, only to watch them flee like a headless chicken, and go around a wall- out of LoS of everyone else, with the monster close behind- quickly becoming a human happy meal. Or they dont look at where theyre dodging, and put themselves in a corner with the monster between you and them- Only to then have unconsensual things acted upon them.
Sunny is all about coordination and positioning.