One thing you can do to make a big boss dangerous is just make normal Hack & Slash useless. Imagine they are fighting a storm giant or something the like, and they normal Hack & Slash, you can just say "ok, you are just chipping his toenails, that is not going to work."
Force them to be creative: climb the giant (defy danger), try to out maneuver it, use terrain to get higher, make it kneel, whatever. It's a giant, it makes sense a normal attack on his foot with a sword is not going to work (even if it works in other games).
About hard moves, I would say the troll hitting is a consequence of them failing. For example you say:
— The troll comes at you with its huge club, what do you do?
— I tumble to the side to avoid it. (player rolls and fails)
And now is when you decide a hard or a soft move. You could do damage, or you could just put the player in a harder situation (you are not fast enough and the club grazes you taking you out of balance, your weapon goes flying and you are now lying on the floor, while the troll prepares to step on you!).
A drone, while kind of squishy, is not totally unable to pat it's head and rub it's tummy (so to speak). It doesn't need an autosoft for most of it's tasks. However, it does seem to need one for firing weapons that are attached to it. You'll need a Targeting autosoft just to make the roll for a drone (note: this autosoft isn't needed if you're jumped into the drone).
As a rigger, you have to choose what to do for drones. Not only can they load up their own autosofts, they can use yours on your RCC as well. The rules do state that a drone can only use the RCC programs if it doesn't have it's own loaded up, but I think it would be easy enough to handwave letting a rigger disable drone programs to override with RCC programs (talk to your DM, your mileage may vary). So, what I would do is this:
Have three groups of drones: air surveillance, ground surveillance, and support.
Air surveillance drones should have a good Clearsight and a good Stealth autosoft (can't remember what the actual autosoft names are). Then, have a Targeting autosoft for them on your RCC, in storage, ready to load up and run when you need it. Do the same with the ground surveillance ones, but I would ready a Maneuver autosoft for them rather then a Targeting one. Finally, for the combat drones, load up a Targeting and Clearsight autosoft and ready a Maneuvering autosoft in case they are going up against things they can't kill outright themselves.
When we get the Cannon Companion or Arsenal book (which I believe is the first splat book slated for release) we'll have a lot better ways to trick out and customize your drones. But for now, use them safely and try to overwhelm opponents. If you can't do this, use your combat ones to Covering Fire and zone control while your actual street sams flank or run away.
First and foremost as a rigger, you are support. Your job is not to blow away targets. It's to light those targets up and inform your group so they can do it that much better. And have autosofts ready to load up into the RCC to get them out of danger.
Best Answer
Upgrading the Pilot program
The simplest solution is to increase your Pilot program, the drones on the core book were all limited to their factory Pilot program (rating 3 or 4), but Rigger 5.0 gave us some prices on more advanced Pilots (p.126). But keep in mind that drones equipped with rating 5-6 are generally military-grade (F) and might cause you some issues.
Using better weapons
Upgrading your weapons will also grant you a few benefits in combat, such as:
Firing modes
I know this is fairly obvious, but using semi-auto and full-auto firing modes will drastically increase the chances to hit a target, as you are effectively reducing their defense pool against your attacks.
With this in mind, grab the heaviest weapon you can that is capable of full-auto as a complex action, and send the same firing command to all your drones. Not only they will have to reduce their initiative in order to gain a higher defense pool, but you might be able to completely negate their defense check by reducing their pool to 0 dice, which means automatic hits with a single success on your attack check.
Sensor targeting
When your drone is targeting, you have two options: Passive and Active targeting. The drone makes a Pilot + Clearsight [Sensor] check in order to find her target, applying a modifier based on the Signature Table (p.184) and check the results based on the type of sensor targeting being used:
Also, keep in mind that for this check to be resisted, the target has to be actively trying to evade your drone. Being Surprised will certainly deny them this chance, and to remove the targeting once it's set, they will need to spend their action to sneak away from your drone. See this awesome video from Complex Action.
Rigger 5.0 adds the option to upgrade your Sensor array (p.123) for rating * 1,000 nuyen, or a single sensor for rating * 100 nuyen. This will replace the original sensor, so it will cost you 4,000 to upgrade from Sensor 3 (factory) to Sensor 4, 5,000 to Sensor 5 and 6,000 to Sensor 6, the maximum available.
About the Smartgun system
All drone-mounted weapons are "smart", you need the weapon to be connected to your drone hardware somehow, and you need software to be able to sense the targets, aim, and fire. But there are ways to make it "smarter", as shown by the Weapon Targeting program example:
The Ingram Smartgun comes with an integrated smartgun system, which will add +2 to its Accuracy (which is already high enough, depending on the weapon). But note that this will not add any dice from the Wireless bonus, as your drone neither has a Smartlink nor an augmentation that grants the benefits of it. So having a smartgun system is only going to benefit the rigger when jumped in.
However, Rigger 5.0 brings you the Smartsoft program (p.127), which is a rating 3 autosoft (1,500 nuyen) that allows all benefits of the smartgun system for drones. Install it and you can now benefit from +1 to your attacks.
If the weapon isn't smart already, like an Ares Predator is, you will have to either mount an external smartgun system (200 nuyen), or buy a version of that gun that has it integrated (twice the weapon's base price).
Disclaimer
As you might have noticed by now, this all costs a lot of nuyen. And even if you build the perfect combat machine, drones are still fairly fragile. Do you really want to have your drone attracting that much attention during missions? I would advise you against that, as not all contractors are willing to pay for your losses during a mission (if any of them are, actually).
You can easily build up a combat drone that costs up to the 70,000s and will still manage to get shot down by a lucky auto-fire's spray of bullets. For that much nuyen, you could have 4, maybe 5, smaller drones well-armed but rolling fewer dice on their attacks, which would still have a greater damage potential than a single heavier drone.