Pushing through a guarded chokepoint is usually a bad idea. But if you HAVE to do it, you must do it as a team. Your goal is to get out of your disadvantaged position as quickly as possible, and minimize the amount of damage your team takes as you go out of the chokepoint.
Here's one way to do it (long explanation incoming, tl/dr at the end):
- The entire team pushes hard out of the chokepoint, firing whenever they can and torso twisting to spread damage. EVERYONE must move, staying behind just gives the enemy an advantage.
- Once out of the chokepoint, most of the mechs go for a flank of the enemy. This has 3 purposes: 1) Going for the enemy's flanks lessens the chance you'll be flanked on both sides as you come out, 2) it unbalances the enemy as they have to adjust their positions to deal with your push, and 3) moving sideways relative to the enemy makes it harder for them to aim for your central torso.
- At the same time, a small distraction force of fast mechs go the other way and try to draw as much fire away from your main force as possible. The longer the distraction lasts, the better.
- Once you've formed your battle line outside the chokepoint, the battle proceeds as normal.
Use anything that will reduce the enemy's advantage as you go out of the chokepoint. Use artillery and airstrikes to disrupt their formation. Blind-fire LRMs onto the enemy to make them go into cover. If you have many autocannons, use it to scare as many of the enemy's mechs as possible into torso twisting or getting into cover. Use anything at all that reduces the enemy's advantage as you push out.
And don't underestimate the fear factor of a big push as well. The bigger and more aggressive your push is, the better. I've seen chokepoint defenders scatter in disarray at the sight of 3 assaults followed by their entire team coming out of a chokepoint with all guns blazing.
tl/dr: EVERYONE pushes, most go towards a flank, fast mechs do a distraction on the other side, be as scary as possible.