Commander Shas'o
Cyonic fusion blaster
airbusting frag projecter
target lock
shield drone x 2
145pts
Drop him down to a shas'el, give him a targeting array, and he's now 15 points cheaper with the same fire power. 3 Weapon options seems to be a waste to me, simply because at most you can only fire 2 in a turn, I'd suggest dropping either the fusion (for him to be anti-horde), or drop the airburst, and swapping fusion for plasma (For him to be anti-teq). He doesn't need target lock, as he's already the one shooting, unless you plan on having the shield drones shoot somewhere
. Drones are good, since they give you ablative wounds.
Troops
Kroot carnivore squad
20 kroot
shaper
6+ save
181 pts
Drop the shaper, and the save, as that's (generally speaking) point sinking, and not all that benefitial. Only a few weapons I can name that doesn't cut that armor, and rarely does it ever help in hand to hand.
2x fire warrior squads
12 fire warriors
1 shasui
bonding knife
285ptspts
Acceptable... Personally I found the 'ui, and bonding knife is often a waste of points... keeping the 'ui for higher leadership isn't a bad idea, unless you plan on mounting these guys in a fish.
ELites
2 x stealth teams
6 stealth siuts
1 fusion blaster
shusvre
384pts
Tau operate best when their unit roles are not split. Keep all suits as burst cannons and have them go unit hunting... Honestly even str 5 w/ 18 shots to back armor often destroys a vehicle. Drop the squad leader, just a little bit more of point sinking here.
2 x Hammerhead gunship
railgun
smart missle systems
flechette dischargers
targeting array
180pts
I perfer the bursts as you get 2 more shots out of the hammerhead, but that's fine. Flechettes are optional as all my opponents if they hear there's flechettes, they learn to just shoot it rather than assault it, or assault it with units that it won't really matter if they take wounds, or are highly unlikely to get wounded (hive tyrant for example). Add in disruption pods... they are a must, as well as multi-tracker. Disruption pod = mobile cover save, awesome. Multi-tracker = able to fire as a fast vehicle, even better...
As far as strategy goes, all I can suggest is go mech... devilfish for fire warriors, and outflank the kroot. Since you said you're being out manuvered by an outflanking unit, and nids. Without hearing you general battle plan it's kind of hard to give tips on your strategy.
Also, seems like all your point values are off...
Commander: more like 157
Kroot: 180 (think you gave 1 extra armor accidentally).
Fire Warriors: 135 (each). (think you added an extra fire warrior or something, as the 'ui is an upgraded warrior, squad size is max 11 + ui = 12).
Stealth Teams: Correct.
Hammerheads: 170 (targeting array comes standard).