No One Left Behind

When I had Legion in the vent and Garrus as the fire team leader they survived.
With the second part, I had Jacob leading the survivors back to the ship (I heard Mordin is a good choice here too, as he often randomly dies in th end), Samara as my Biotic specialist (Jack also works here), and I picked Thane as the squad leader, but this is a BAD idea, as it gets him killed. I heard that Garrus or Miranda work pretty well here. Your last team to fight the boss with you isn't a huge problem, but I think if Mordin didn't lead the survivors back, you should pick him, since, once again, he can randomly die in the end.

Hope this helps.

I've got a shortlist of who to pick where. Keep in mind that for everyone to survive, you need EVERYONE loyal, and you need to purchase the cannon upgrade (Garrus gives you this), Armor Upgrade (From Jacob), and shield upgrade (from Tali).

Tech Specialist - Legion or Tali
1st Team Leader - Garrus, Jacob, or Miranda
Biotic Specialist - Samara/Morinth or Jack
2nd Team Leader - Garrus, Jacob, or Miranda
Person to Lead Normandy Crew Back - Any Loyal character (Mordin is suggested here, as he has a high chance of dying at the end of the mission if he doesn't. Jack and Tali are also good choices.)

Boss Team - Any two loyal members. At the end, there's a way to decide if anyone died defending the door based on everyone skill at "Holding the Line", so if you take Grunt (Perfect Krogan Soldier) and Garrus (Held two merc groups at bay by himself for over a day), that leaves lots of people less adept at holding the line, and someone could die. Therefore, it's good to select from Mordin (although he should have been sent back by now), Tali, and Jack, as they, according to the designers, have the lowest skill at this and are likely to die).
TL;DR - Tali, Jack, and Mordin are best here.

^do exactly what this guy is saying cause that is how your going to beat it also make sure you have all ship upgrades and squad custom weapons, and that I recomend using the M-902 CAIN(not sure if thats the right numbers my TV is a small piece of crap) it is extremely useful for the boss at the end, so don't waste it on those little guys. I recomend trying to keep mordin with you most of the time because I find he dies very often.

Good luck to all trying this it was a pain for me too.

When you do the I ff mission after that do Legions mission then do Tali's mission and take legion. But I didn't have everyone loyal as I failed Samara's and Thane's and Jack got taken away by the swarm after Jack and Miranda got in a fight. So do Miranda's mission then Jack's. At the end of the Suicide mission I saw the collectors run past Tali's body who's my favorite character. I almost restarted the mission.

Another tip After you do the I ff mission strait away do Legion's mission and straight after do Tali's and do NOTHING else not even scan a planet and your team shouldn't be kidnapped.

Uh, just make sure their loyal and make logical choices. Also, send Mordin back to the ship with the survivors, he doesn't often do well in combat.

When I did it everyone but my loyel team mates died so all you have to do is have every one loyel and nobody should die.