The drone has a Flash Pulse and Electric Pulse as weapons. Given it also posses Mimetism and an above average WIP of 13, it is more likely to stun an enemy than it might at first appear. In melee it's poor CC stat means it will almost always be better to use Electric Pulse and hope for a poor roll from the opponent (a 35% chance) than to try and fight it out.
Mimetism will help against shooting attacks. Drones are almost always better shooting than Dodging, if they have the option, because of the usual -3 penalty on Dodges and Change Facings that REM troopers suffer. A drone's Silhouette is vertically smaller than a standard trooper making it easier for them to take some kinds of cover, which they will need as they cannot go prone.
Because it has Structure instead of Wounds this unit possesses a second Unconscious state. In effect, it takes one more wound than normal to remove them from the table. It also ignores the "straight to dead" effect of Viral and Shock ammunition.
G: Remote Presence grants Courage meaning it can always choose to not take a Guts roll.
R-Drones can be used to expand your hacker's reach allowing them to hack through it's Repeater and gain a fire-wall bonus against enemy responses. Spending a few orders (ideally as part of a coordinated order) to move the drone up field and out of sight can slow the advance of enemy HI, REM, TAG, and Hacker units.
The R-Drone can place a Sniffer as a short skill or ARO allowing other models with Sensor to perform Sensor Sweep in within the ZoC of the Sniffer. Sniffer's also prevent enemies from Re-entering the camouflage state so it can help to limit enemy options.
With a Supportware program such as Overclock, the R-Drone's flash pulse can become a pain for the enemy, stunning their troopers and preventing Rambos from running your board, but it is best not to rely on this tactic and provide too many easy kills for your opponent.
Always remember that you can Engage with a drone and do not suffer a -3 on the PH roll to do so. This will usually doom the drone, but it forces an enemy to spend orders to get out of CC with them which can let your other troops Dodge out of LoF, deploy mines, or even fire into the melee and possibly kill the enemy.
R-Drones are easily killed by most attackers and since they represent bonus orders for your opponent it is always worth doing so. Keep in mind that their flash pulse is at a high effective BS (13 with a long +3 range band) and it is advisable to avoid taking multiple shots in ARO when you can. Also remember that it takes one more wound than normal to completely kill a trooper with Structure, so engineers may come an undo your work unless you confirm the kill.
R-Drones do well in most lists even without a hacker or sensor. They provide cheap orders and a good ARO defense compared to a line trooper, even if they are somewhat harder to hide. For most lists, it is good to consider a 25 package of a R-Drone and a M-Drone to make the best use of the M's Sensor and Sat-Lock skills.
Since they cannot go prone R-drones should be placed with full cover in mind from long range shots. They work as good deployment zone and table edge guards with their flash pulse shutting down enemy attacks. If you are planning to use one to extend a hacker's hacking area you will be tempted to put it on the edge of the DZ, but always consider where the enemy will ARO from. It is better to take an extra order to avoid getting killed on the way in.
Active Turn Role
R-Drones can aggressively move up table to extend the range of hackers or sensors, but they are best served moving as part of a coordinated order when they can be moved up safely. Their Flash Pulse is not amazing and using it offensively should be a tactic of true desperation only.
Flash Pulse is almost always your best option. Even against an opponent in Partial Cover and with Mimetism you are at even odds to your Dodge.