Btw, here is the status effects from the INI if anyone was curious.
BLEEDINGOUT_TURNS=4
BLEEDOUT_BASE=50
BLEEDOUT_SIGHT_RADIUS=3
BLEEDOUT_ROLL=100
BLEEDOUT_BONUS_ROLL=50
BURNING_TURNS=2
ACID_BURNING_TURNS=2
CONFUSED_MOBILITY_ADJUST=-5
CONFUSED_WILL_ADJUST=-3
DISORIENTED_TURNS=2
DISORIENTED_MOBILITY_ADJUST=-6
DISORIENTED_AIM_ADJUST=-25
DISORIENTED_WILL_ADJUST=-30
POISONED_TURNS=5
POISONED_MOBILITY_ADJUST=-4
POISONED_AIM_ADJUST=-30
POISONED_INITIAL_SHED=0
POISONED_PER_TURN_SHED=20
POISONED_DAMAGE=1
POISONED_INFECT_DISTANCE=1
POISONED_INFECT_PERCENTAGE=100
BOUND_MOBILITY_ADJUST=0
PANIC_WILL_ADJUST=-2
STUNNED_WILL_ADJUST=-40
PANICKED_TURNS=2; 1 more than intended as its removed on Begin turn, so 2 results in 1 turn of panick
PANICKED_AIM_ADJUST=-25
PANIC_SUCCESS_WILL_MOD=30
On the higher difficulties, for the first dozen missions, I brought 2 nades and 2 flash bangs. As you can see from the disoriented stats, flash bangs are pretty essential. (Someone mentioned them earlier and was spot on.) -25 Aim, but more importantly it halves their blue line mobility, making it very difficult for them to flank you unless they are already on your dick, it also makes lancers have a much rougher time meleeing you. This is really important because you don't have to waste an overwatch to keep them pinned, instead you can flash and you get the extra defense from the aim penalty and effectively get the effect you want from overwatch (Except for the rare instance overwatch does damage early game.) Best part is flash bang radius is massive and it doesn't affect your own troops.
That said, poison is also awesome. -30 aim and -4 mobility, for 5 full turns, as well as 1 damage per turn. So actually more powerful defensively than flash, but it's got a tiny radius so I think flash wins.
Also, the overwatch penalty is -30%, not -30, but a straight 30% drop like deadeye's 25%. So if you overwatch with 100 aim, you get a 70% chance to hit. If you overwatch with 50, you get a 35% chance to hit. So it scales down with shitty aim and scales up with better. Overall, the whole concept of overwatch ambushes unless you have the time to do them on the enemies turn should probably be avoided by your high hit (Sniper) characters, and your lower hit characters are probably better off flanking unless you're really being cautious about extra pod activation.