All that’s left to do now is the Mirror Match for the " One and Only " trophy/achievement. If you want to make things easier, add the enhanced player damage modification to do extra damage to your opponents.
Select a mixed squad for the next battle because you will face off against each of the six classes who happen to be Shepard clones. They will use all the skills available to that class (yes, even Biotic Charge) so a way of stripping shields and doing extra damage to armour is a must. Energy Drain will also help a great deal in this fight. Blasteroid is a good map.
The first wave will have Engineers, Adepts and Soldiers. The Adept is probably the most dangerous as his biotics are incredibly strong. He also uses the N7 Hurricane SMG as his weapon which is absolutely deadly up close.
The Engineer and Adept have very little in the way of armour so strip their shields and place a few good shots into their skulls. The Soldier has a fair amount of armour but is not much of a threat unless he catches you unawares.
They will split up and go in opposite directions to attempt a flanking maneuver so to prevent this you must keep moving. Keep a sharp eye on the spawn zone for the next group and to plan which direction you should move next. Do this throughout the fight.
Whenever you move, make sure your squad move with you so they will cover you if things get tight. After you’ve finished off the last guy, a new wave consisting of Infiltrators, Vanguards and Sentinels will begin.
During this wave, be incredibly careful when sticking your head out of cover because the Vanguard will biotic charge your position and then proceed to Nova you right in the face. If you see him charge, dodge out of the way and run to another position. Do not allow him to Nova you as you will die.
The Sentinel then provides the next deadliest opposition. Be careful as they have a nasty habit of attacking you from behind while you’re preoccupied with the Vanguard. As you would expect, they have a lot of armour and take some killing so let loose with tech bursts to bring them down.
Lastly the Infiltrator is surprisingly the least bothersome as they have a tendency to just stay in cover, making the odd potshot for your head with a sniper. They can cloak and often do, so just be aware of that when running to a different position as they may be waiting for you. They have a tendency to spam Incinerate as well.
In the final wave, all six classes are present. Try and take out the squishiest ones as soon as they spawn (Adept and Engineer) and then focus your attention on the Vanguard and Sentinel. Once you manage to take down the Vanguard, things are less worrisome.
As before, move around the map, taking your time to plan each movement. Check where all the enemies are first and then make a break for it. Keep a healthy distance between you and them and eventually you will emerge victorious with your trophy/achievement and probably a rather nice score to boot. Well done!