Tying into my post on
Broadsides vs. Frontal Assaults, here's one on the use of debuffs and buffs within a group setting. Mind, I'm not as familiar with these skills as I am with weapon performance/enhancement, so I may get some of it wrong, hence the "theory" part of the title.
A Buff is usually something that helps to keep yourself or a friendly ship in working order, usually by increasing damage resistance and increasing regeneration/repair over time, but also in that they can repair damaged subsystems such as shields or weapons.
A Debuff is something that lowers resists or disables an enemy ship in some fashion.
In practice, you use these abilities on opposing/friendly ships to weaken/strengthen them to make them easier/harder to kill. There's a wide variety of both sets, from all career paths for both Officers and Players, and there's quite a bit of counter/re-counter mixed in to keep things interesting.
Stacking Buffs/Debuffs
Now, I know what you're thinking; "If I have support abilities, I won't be able to keep myself alive" and this is true in a sense, but worth considering is that no matter what buffs you have on your ship, your team mates stacking buffs on top of you will produce a far more powerful and redundant tank than anything you could ever manage on your own. This is only possible if you work together to achieve this though and you can only work together if you can properly support one another.
Good news is, pretty much every ship is capable of supporting a teammate, even a hardcore Tactical Captain and his Escort.
Even an Escort can be a tank if half of it's crew consists of Science and Engineering Teams.
On the flipside, you have debuffs, such as Attack Patterns Beta and Delta. These weaken an enemy target and I believe they also stack, even going so far as to result in
negative resists. These abilities are strong in the sense that they throw off teamwork. Most times, people will react to concentrated enemy fire. They aren't quite as ready to notice debuffs being stacked on an ally while a lone Escort is bearing down on him, tactical abilities locked and loaded.
Also worth noting is that, I believe, that some resists debuffs result in shields being weakened across the board. Meaning that even their kinetic resists drop. Meaning that torpedoes will be doing full damage
to shields. Reverse Shield Polarity isn't worth anything against that.
And, as a curiousity is the seemingly underrated Boarding Party/Security Team abilities. The question is; what happens to a ship that has been successfully boarded by 20 or 30 assault shuttles? Nothing good I wager. Viral Matrix that stacks and has a short cooldown maybe? Your team could take an enemy ship completely out of the fight for a period of time and do so again before anyone is the wiser. Naturally, it's best to let the boarding parties sort out the enemy ship before destroying it, so intiating a boarding against a high tier support ship would probably be best.
Concerns
To be honest, I'm not sure how stacking is treated with either Buffs or Debuffs. Whether both stack, only one of them does, if there's a hardcap in there somewhere (negative resists?), etc. These would have to be answered by experimentation within a team setting.
Personally, I suspect that debuffs stack more strongly than buffs, but have a hardcap. This isn't from in game experience, but my experience with games and mmos in general.
The Torpedo Boat.