Spoiler free incase some people haven't played this before.
Tips for Insanity:
Make sure you equip Wrex with highend gear before the mission starts as he makes mincemeat of the boss if you can keep him free of Geth adds.
For the mission itself I took Ashley and Tali (I was playing as an Biotic) Tali is handy for creating a diversion for Geth by hacking a rank and file Geth unit. Ashley provides the muscle. Make sure you have Throw and either Singularity or lift to at least 11 before starting the missions. Lift and Throw are almost invaluable but Simgularity at a ride range can be much more helpful in the final boss.
Boss Tips:
• Make sure both followers are only attacking the Boss
• Only attack unit close enough to you that the may flank
• Use barrier as often as poissble (Immunity if you're a combat class)
• Take Wrex with you, he must have health regen upgrade on his armour, High explosive or pyro ammo for his main weapon. Second rank of Carnage and at least level 11 barrier.
• I took Garrus with me during this sequence but Tali with decent armour would suffice.
• Try to use barrier to run through the Geth that land from the drop ship, I found thr area where the Normandy previously landed has the best cover for the task at hand.