Cerberus is the easiest gold challenge to complete. Often time Geth are attributed to be the easiest, and that is true on the bronze and silver challenge, but on gold they can overwhelm even the best team. Cerberus is easier because most biotic powers are in some way effective against them.
For any gold challenge you need good teammates. If you are using the inbuilt match making system you usually end up with fairly bad players. You probably will never finish the gold challenge with random teammates unless you are incredibly good or come across some good randoms.
First follow the guide I wrote about carrying your team. You can find it here. I also suggest that you only try the gold challenge once you have ranked your class all the way because the power buffs are very important for the gold challenge. Also the more missiles and self revives etc you have per mission the easier it makes the gold challenge. These come with buying upgrade packs.
Effective Classes Against Cerberus
The vanguard shines against Cerberus. None of the enemies except the Atlas stagger you. This means that you can charge anything except for the largest groups of enemies. I usually like to wait a minute or so to let them thin out a little and shoot them with my pistol from behind cover. After that you can safely start charging around. Be sure to note the position of turrets because you will die if you charge them. Be sure to kill any combat engineers you come across. You want to direct your nova towards cover which you can use in that final instant that charge isn’t ready in after nova. You can also barrel roll around a corner to avoid fire. Don’t charge bunched up groups of enemies because they will down you in that instant that charge isn’t ready. And nothing but an infiltrator will be able to revive you. Also, don’t charge Atlases. They can stagger you and instantly kill you. Let your teammates take care of them
Overload is very good against Cerberus. Only the Atlas has armor so it will either damage shields and barriers or stagger enemies which allows you to kill them with pistols without having to worry about them shooting you. You can find a comprehensive guide for using overload here.
Sniper rifles are also very powerful because Cerberus tends to have slow moving enemies. You can find a guide about the effective use of sniper rifles here. You can also shoot guardians easily through the slot in their riot shield. You need an infiltrator to take care of the multiple part objectives and to revive downed teammates. The cloak recharge time is short enough that using a heavy weapon isn’t going to impact your effective use of the cloak. The best infiltrator is the salarian infiltrator because he has a proximity mine which is very useful in all sorts of situations because it is a power rather than a grenade so you have an unlimited supply of the mines. You can find a class spotlight for the salarian infiltrator here.
Cerberus Gold Challenge Combat Tactics
What will kill your team is if an Atlas gets near the main body of you squad or if you get overwhelmed by phantoms which can instantly kill you and usually down you quickly if they get close to you. Their attack also staggers you. Turrets are also very deadly.
The vanguard can easily take care of any number of phantoms. Charge and nova staggers them and lets you charge about a group of phantoms indefinitely. As a vanguard be sure to take care of the stronger enemies and large groups of enemies so that they can’t push your squad around the map.
The engineer is perfect for taking out turrets. However, before focusing on the turrets be sure to kill the engineers. They will repair turrets and Atlases if they are close to them and they have a seemingly infinite supply of more annoying turrets.
The Atlas is best taken care of by either using warp and any other biotic power if you are playing as an adept. You should always have an adept supporting the vanguard because if you put warp on one enemy in a group the vanguard is charging it charge and nova will trigger biotic explosions which can kill lots of enemies very quickly. The best adept is the drell adept. Either pull or reave will set off biotic explosions. Reave also works on Atlases. You can find a full guide for the drell adept here.