Just did a load of CheatMod testing on this. While I still don't care for the OP's attitude and tone I can understand their frustration now. Five SU-76s are very, very strong against the entire Ostheer vehicle arsenal.
I set up the following experiment. I found an area of open terrain on the Moscow Outskirts map. I turned Fog of War off so that every vehicle could fire at maximum range. I set up a line of enemy controlled SU-76s, then attacked them from the front with varying combinations of Ostheer vehicles.
My discovery was thus: if you charge five spotted for SU-76s over open ground with less than 375 fuel worth of vehicles (the price of five SU-76s) you will lose.
Four StuGs? Dead. Two Panthers? Oblitered. Elefant? Annihilated. To beat the SU-76s in their element required more than the 375 fuel the SU-76s cost. It wasn't possible to play their game and come out on top.
Why is a swarm of SU-76s so powerful? The two obvious answers are range and penetration. The SU-76 can penetrate the frontal armor of an Elefant and its greater range means it gets to shoot at approaching vehicles when they can't fire back and those vehicles often get movement penalties when they do return fire.
Vehicle pathing also works against attacking armour. If you attack the SU-76 position with a group of vehicles they like to form a line. This plays straight into the SU-76's hands: they can kill the vehicle at the front before the vehicles at the back can fire and then repeat this for the next vehicle. The vehicles need to be commanded individually to prevent this suicide conga, adding an extra micro burden to the attacker.
The last two strengths of the swarm suprisingly enough come from the SU-76's weaknesses. The low armour of the SU-76 works in its favour. Late game armour like Panthers pay for their high penetration (they'd cost less if their penetration was lower) but get no value from it against paper thin SU-76 armour. The low health of the SU-76 is also an unexpected strength in numbers: any damage in excess of the SU-76 isn't transferred to another and is wasted, turning the slow firing high damage guns of the Axis tanks into a disadvantage. I call this their "overkill advantage."
So how can we turn this knowledge to our advantage?
- Don't engage them on their terms: if you attack an equal fuel investment of SU-76s over open ground with spotters for the SU-76s in place you'll lose.
- Use smoke. Smoke proved invaluable in testing: by blocking their line of sight you can close in without being fired on. If your StuGs can close to firing range without being fired on and can avoid moving more than the SU-76s they've got a good chance of winning. In addition to covering your advance you can use smoke to save your wounded vehicles and split the SU-76 pack up. The swarm is much less powerful when you fight it one or two at a time.
- Defeat them in detail. Every SU-76 you blind with smoke is less firepower the pack contributes to the fight. Invoke Lanchester's Law to your advantage.
- Try to fight the SU-76s with a similar number of vehicles. More guns means a lesser overkill advantage for the SU-76s and a greater overkill advantage for you. I found Pumas and StuGs to be the most effective options.
- Use infantry anti-tank whereever possible. Two Panzergrenadier squads will beat five SU-76s in isolation and are very useful in an actual engagement. Panzerfaust equipped troops are also very useful: if you can finish off a wounded SU-76 with a Panzerfaust you're not going to waste tank shell damage on overkilling it.