Some thoughts from reading through. I'm assuming the shaded tanks are already set, so I won't talk about those.
Silver - I don't think cloak is a very newbie friendly skill, it takes some practice to learn timing and limitations. Perhaps a sort of EMP (I think you named it disarm) that disables nearby enemies (or maybe wipes nearby bullets) for a short period? To prevent abuse, you could have enemies become immune after one use.
Corsair - T2 and T3 don't really seem to fit with a forward oriented style, could do some kind of "ram" attack, charging forward, or maybe one that redistributes front shields to general shields (though that might be too much with T0).
Hurricane - All pretty cool, though T3 shield regen is kind of useless in the middle of a fight unless you've just used the disarm. Since it's about mowing down large mobs, it could have a trigger that makes all shots bounce to nearby targets, which fits with the name and concept. Could also be a damage buff that scales with the number of nearby enemies.
Hercules - One of these has to be a manual drop/detonation of the bomb, no question about it. Since it seems mostly about slowly wearing down enemies, T3 could drop a special bomb whose bullets inflict a DoT, or maybe even changes a part of the ground, which does DoT to enemies on it. Another possibility would be a generic reflective armor buff that reflects damage back to attackers. Something that might be OP would be a bomb that pulls nearby enemies towards it for a certain time.
Scorpion - Since there's no theme posted, I'm assuming scorp is designed after artillery. Sit back and blast things from far away, preferably behind someone big and tanky. I think a trigger for range boost would be nice. A fortify option would be useful, increasing offensive stats at the cost of movespeed/defense. Something that disables enemy movement/offensive capabilities based on your own attacks would also be fitting.
Cobra - Seems like it should be a glass cannon, so the heal doesn't really fit. If it gets healing at all, it should be stealing hp from enemies hit.
Spectre - An interesting trigger would be an instant 180 spin. Offensive/defensive sides switch, and strong/weak switch. Since's it's all about the angle of attack, a movespeed boost would be nice, as would a turnrate boost.
Avenger - Gets a damage/rate of fire boost that increases when you've lost more shield segments, which makes people decide between spinning around to get more firepower or stay put and stay safe (fits with the name, and because circling is boring
. If you are going with the circling route, though, a trigger to redistribute full shields to lost ones would be helpful.
Wolverine - Dunno if it's possible, but temporarily allowing the secondary turrets to rotate 360 would fit well with the theme. A trigger that disables the main turret to power secondary turrets or vice versa would be interesting, giving the choice between being better at fighting single targets or crowds.
Phantom - A trigger that removes unit collision would be hilarious. Fitting with the name, and essentially gives you a melee single target nuke for enemies that are big enough (basically a temporary SoEP). Not sure if this is possible, but having shots change priority to farthest instead of closest and make them piercing would be cool. Or just make shots deal AoE.
Valkyrie - Haven't played valk much, seems to use shotgun as damage dealer while circling with front guns to clear the path. Based on that, some useful triggers would be removing unit collision, boosting turn rate, and maybe have something to slow down enemies.
Predator - It's limited to frontal assaults, without the firepower of the Cobra. A trigger that charges at and damages enemies, a trigger that pushes away enemies at the sides/back, and/or a trigger to "snipe" a certain percentage of hp from an enemy in front would give it some utility that the Cobra lacks.
Pegasus - The only way to constantly heal someone would be to circle them, which is weird to me. Healing fore/aft and damage left/right would let you follow someone around (or have them follow you) and help protect their flanks, which would be immensely useful for tanks like Cobra and Predator. As for triggers, the only ones that come to mind are an instant group heal, a damage reduction aura, and perhaps something that gives additional benefits to targets healed (movespeed, damage, etc).
Peacekeeper - This confuses me more than the Pegasus. Why would you need more shields on the side that should be facing allies? Why is healing limited to one side when damage turret can 360, effectively letting the healing go in any direction while still firing? For triggers, a 180 spin like the Spectre, a healing shotgun, and maybe a shield transfer to allies would give it some nice options and distinction from the Pegasus.
Wildfire - I probably play on this guy the most, because of the capability to handle both single targets and crowds fairly well. If you're focusing on the front, then triggers to repair the front shields and some sort of AoE shotgun/bomb would go far.
Viking - Pretty sure this does the most single target damage except for maybe avenger. Since it's focused on single targets, a sniping trigger would fit well. To distinguish it from the avenger, it could have a trigger that instead of being more useful as you get more damaged, be more useful as your target gets more damaged (ie, damage boost increases when your target has less % hp).
Fury - Every good broadsider should have good movement mobility, possibly a back/side blink, and allow disabling one side to get more damage on the other.