Loadout:
Shotgun / Bullpup Rifle
Grenade Launcher

Squaddie:
Blast Padding
Launch Grenade

Corporal:
Reflex (+1 action when fire at, once per mission without skirmisher rebalance)
Flash Round (Take a shot with +15 aim, does no dmg but can disorient a target)
Sapper (+1 dmg with grenades)

Sergeant:
Lightning Reflexes
Breaching Round (destroys cover)
Remote Start (blow up environmental objects and make them do more damage)

Lieutenant:
Deadshot (+10 crit chance)
Flechette Shot (deals -3 damage but is a wide accurate shot over a wide area)
Heavy Ordnance

Captain:
Untouchable
Ever Vigilant
Volatile Mix

Major:
Storm Position (dash up to an enemy and attack them with your primary weapon)
Extra Layers (+2 armor)
Salvo

Colonel:
Rapid Fire
Explosive Shot (Deals double damage & ruptures a target)
Shredder Blast (Destroys cover and damages enemies in a wide cone)

GTS:
Biggest Booms (gives grenades a 20% crit chance)