Creating Custom Swarms for Upcoming Mass Battle

I have a pretty climactic battle coming up, as a conclusion to my first adventure. It's from an old 2E adventure that actually was poorly written, but has played pretty well regardless. The last battle is supposed to be a somewhat of a large scale skirmish. Sort of. There are roughly 70 troops on the bad side, and about 60 on the good side.

So, what I need to do is make a few custom swarms to reflect the different types of military units used in the battle. I've worked on this a little, but I have to admit, I'm floundering a bit. I want these "swarms" to have some pretty cool attacks and abilities -- at least in my eyes. Here's what I have so far on two of the groups.

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Orc Infantry Platoon
Level 2 Brute
Medium natural humanoid
XP 125
Initiative –1 Senses Perception +0;low-light vision
Swarm Attack aura 1; each enemy that starts its turn within the aura takes 5 damage.
HP 50; Bloodied 25
AC 17; Fortitude 12; Reflex 9; Will 9
Resist Half damage from melee and ranged attacks.; Vulnerable 5 against close and area attacks
Speed 4
Overwhelming Assault (standard; at-will) • Weapon
Close burst 1; +5 vs AC; 1d10 + 3 damage, and the targets are pushed one square. The Orc Platoon can shift 1 square into the space vacated by the targets.
Warrior's Surge (standard, usable only while bloodied; encounter) • Healing, Weapon
The orc platoon makes a melee basic attack and regains 19 hit points; +5 vs AC; -2

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Orc Archer Squad
Level 2 Artillery
Large natural humanoid
XP 125
Initiative +3 Senses Perception +2;low-light vision
HP 49; Bloodied 24
AC 14; Fortitude 15; Reflex 14; Will 15
Speed 6
Shortsword (standard; at-will) • Weapon
+7 vs AC; 1d4 + 3 damage
Shortbow (standard; at-will) • Weapon
Ranged 15/30; +9 vs AC; 1d8 + 2 damage
Concentrated Volley (standard; at-will)
Ranged 15; targets two creatures; +7 vs Reflex; 3d8 + 3 damage,
Rain of Arrows (standard; at-will)
Area burst 2 within 15; +5 vs Reflex; 1d8 + 3 damage
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I could use all the help y'all are willing to dish out.

Thanks in advance

These seem slightly low-powered for a whole squad of orcs, with the exception of the Volley.

I would consider a squad of orcs at least an elite, if not a solo, at level 2/3. A level 2 standard monster just doesn't seem to do it justice.

Also: a medium platoon? that means you've got a whole squad of orcs (which are not small by any stretch) fighting out of a single 5x5 square?

Also, the Concentrated Volley power of your Archer Squad is significantly more damaging than expected for the level, 3d8+3 to two targets (who needn't even be close together), at will, is huge. It really does seem like elite/solo territory. And even then, the damage will probably need nerfing somewhat.

Personally, I'd probably go with a few elite versions of Orc swarms, and some Orc Drudge minions

To be fair, these were the only squad's I've worked up. There are 4 other squad types I need to do. Additionally, the player's also have to worry about taking out the BBEG and his two bodyguards.

And you can skip over the size, I forgot to change that in the builder. That's my bad. I know the swarm is supposed to represent (traditionally) several "small" creatures attacking en masse, like rats (which I would classify as tiny, but w/e).

Like I said, I just grabbed what I had so far. I'm very new to monster building.

To further clarify things, here's a run-down of the mobs the characters will have to chew through:

1 platoon of orcish infantry
1 platoon of orcish archers
1 squad of goblin cavalry (mounted on wolves)
2 squads of human infantry (half a platoon)
1 squad of human light cavalry (horses and lances)

Additionally:
1 Level 5 Big Bad Evil Guy
2 Level 3 Bodyguards for BBEG
1 Platoon of Personal Troops to command. (optional)

PS: Regarding the Concentrated Volley, good point. I'll decrease it to 2d8+3, and change it to read "two adjacent targets"

What I'm having trouble with is creating the powers.

Lets take the Orcish Infantry Platoon.

I wanted to represent the fact that, as a melee unit, 24 or so orcs would constantly be fighting something, hence the swarm aura.

I also want the infantry unit to be able to push the attack forward, forcing enemies back into an inadvantageous position. -- hence the area burst attack.

I want the infantry unit to be able to "rally for reinforcements." Essentially, when things start to get tough, they thematically call for backup, and mechanically get more hitpoints. I'll probably extend this ability to the other units.

However, those are only a few attacks. I want to throw in some recharge abilities, and some encounter types, but I'm stuck as to what to add. This is where I need help.

Just did a quick work-up of the Human Light Cavalry, here is my rough draft proposal, but First, some key points.

Single target attacks don't really work for "swarm mobs." The idea is to have the attacks affect the full line directly in front of the mob. I've no clue how to work this out effectively.

I wanted some kind of "ride by attack" where the cavalry unit will sweep the battle field, with the desired effect of plowing through/over all enemies on the field. I'm not sure how to effectly resolve this.

Human Light Cavalry Squad
Level 2 Elite Skirmisher
Huge natural humanoid
XP 250
Initiative +8 Senses Perception +6
HP 61; Bloodied 30
AC 16; Fortitude 14; Reflex 15; Will 13
Saving Throws +2
Speed 8
Action Points 1
Lance (standard; at-will) • Weapon
Reach 2; +7 vs AC; 1d10 + 3 damage, and the target is marked until the end of the human cavalry's next turn
Lancer (standard; usable only while mounted; at-will) • Weapon
+7 vs AC; 1d10 + 3 damage, and the target is knocked prone
Champion's Retort (immediate interrupt, when an enemy marked by the human cavalry makes a melee attack against an ally adjacent to it; at-will) • Weapon
Targets the triggering enemy; +6 vs AC; 1d6 + 3 damage
Pressing Charge (standard; at-will)
The Cavalry moves up to 8 squares and makes a Lance attack at any point during that movement. The Cavalry doesn’t provoke opportunity attacks when moving away from the target.
Hasty Parry (immediate interrupt, when an enemy marked by the human cavalier makes a melee attack against an ally adjacent to it; encounter)
The triggering enemy’s attack targets the cavalier instead of the ally, and the cavalier gains a +3 bonus to AC against that attack.

Out of interest, how hard do you want this combat to be? High risk of death/failure?
Low risk?
Not quite risky, but feels that way at first? (squads could easily lose powers as they weaken)

I'd say a moderate risk of death. With some effort at strategy and collaboration, I'd imagine they'd have only slight difficulties battling the enemies.

However, I really would like for them to reach the Big Bad Evil Guy. Imagine a pitched battle, with both sides clashing in the middle of the field. At one end are the PCs. At the other end, the BBEG is laughing it up, causing a riot. The PCs have to wade through and probably defeat all the competition in between, in order to get to him.

The battle is the end of the adventure, and everything the PCs have done so far has built up to this. I just want it to be really awesome. I honestly don't want to "kill" the PCs, I want them to have fun and enjoy it, but I don't want it to be a cakewalk either.

So to sum it up, I'd pick option three out of the choices given.

Here's another one. This time it's a halfling archer squad. Similar to the orcish one though.
Attached as an image -- to lazy to reformat RTF export

Again, and I cannot express this enough, I would really appreciate extra pointers on how to make this work. Much appreciated.

I did something similar a while back, using OneBadEgg's Hardboiled Armies (for the most part). The PCs were commanding a ragtag militia against a much larger, more experienced army from a bigger town. It went surprisingly well, and I think they want to try it again sometime.

The trickiest parts are the length of a turn (I used six hours) and the scale of the squares (hexes, in my case). I wanted to implement fatigue in some form, but couldn't figure out a way that wouldn't be a pain to track and no fun to deal with. Ranged attacks are also problematical, depending on your scale.

The PCs bounced all around the battlefield, inspiring, adding to attacks and defenses, harassing the enemies supply lines, etc. The battle looked really bad for a while, but the bad guys lacked the key ability to heal, and eventually wore down.

I've attached a file that shows some of the units I used. PM me if you have any questions.