Section L. - Countering the Pyro (Work In Progress)
I will eventually write out a bunch of strategies for these classes in detail on how to beat us. But for now I'll simply grade the "trees" to the best of my knowledge on their survivability against us. (Vanish is not taken in to consideration here for OPs and Sins). Survivability for the healers simply entails if they can survive long enough for help to come and support them.
Advanced Protoype: Moderate
Section M. - Leveling as Pyro
A lot of players wish to flat out level as Pyro the entire way, which I whole-heartidly recommend. My personal preference is Shield but that is only due to the soloabiliy of Heroics. However, that is not to say Pyro lacks a lot. It just requires you to be more careful in the way you play.
Your main companions will be Mako, Torian or Gault. Both Skadge and Blizz won't do much to help you as even geared out they go down pretty quickly without you being a healer.
I always preferred Mako, it allows a bit more wiggle room when fighting elites or champions. Both Torian and Gault are great companions, but on tougher encounters it becomes a "kill them before they kill you" mentality.
In the event you are fighting an elite the *easiest* way to manage your companion is have them open up on the target and use any defensive (or offensive) cooldown they have. When they drop to around 30% or so use your taunt. Do not attack until this point, it gives you a good amount of free damage on the target before it starts beating your face in. Otherwise after that just damage it normally.
If you are using Mako, be sure to uncheck any of her damaging abilities. While she'll still take a pop shot at the target occasionally, she'll cast her heals more frequently as her GCDs aren't bogged down by casted damage abilities.
There are a few ways you can level your character. I'll post one of the ways here, for every 10 levels so you can get an idea of what works out really well. I'm keeping these builds mainly PvE orientated from a leveling perspective.
Level 20: http://www.torhead.com/skill-calc#301ZZfhM0z.1
Burning Gas > Iron Fix > Superheated Gas > Sweltering Heat > Incendiary Missile
Level 30: http://www.torhead.com/skill-calc#301ZZfhrbzG0z.1
Superheated Rail > Gyroscopic Alignment Jets >Prototype Particle Accelerator > Rapid Venting > Firebug
Note: If PvP Replace Rapid Venting with Infrared Sensors
Level 40: http://www.torhead.com/skill-calc#301ZZfhrbzGhrs.1
Firebug > Rain Of Fire > Burnout > Automated Defenses > Thermal Detonator
Note: If PvP, replace Automated Defenses with Energy Rebounder
Level 50: http://www.torhead.com/skill-calc#301bMZMsZfhrbzGhrs.1
Puncture > Rail Loaders > Prototype Burn Enhancers > Prototype Cylinders > Intimidation
If you noticed the final 50 Build does use a 4/6/31 set up. With your stats generally being so low, especially aim, you'll gain more from a 4/6/31 build than a 7/3/31 build.