On
easy normal:
Red-Tail (Kestrel Type B) with 4 Basic Lasers
2 Human Crew , 1 Mantis, 1 Energy Guy
Assignments
Human 1 : Pilot
Human 2 : Guns
Energy Guy : Engine
Mantis : Temporary Shields
Early goal:
Crew Teleporter
Another Mantis
Sensors Level 2
Then you can start working on Shields Rank 2 for extra durability or Engine for dodging.
But I prefer to get Crew Teleporter to 2 so I can warp my team out if the boarding goes south.
Early game attacks:
Your quad lasers should always fire upon their guns.
This would minimize the amount of damage taken, aside from the initial volley of missiles etc.
Once their guns are down, you have the choice of continue pounding on their guns to keep it quiet, or hit their engines to prevent escape. Most of early sectors are easy kills, take advantage of that and explore fully before the rebel waves catch up.
For weapons upgrade - you can ignore most of them and prioritize Cloaking Device and Drones.
Drones are for anti-missiles and should not be ignored.
While Cloaking Device will let you evade the initial volley before your guns shut down theirs.
But remember that
FIRE BOMB is crucial for the finale.
Boarding Plan:
If you have Cloak and your Mantis crew ready - most encounters should not be too hard.
Fire all guns on their guns.
If they fire - use cloak to evade.
Once their guns are taken down, teleport your mantis on their gun bay immediately to prevent repairs.
Also STOP FIRING IMMEDIATELY. YOU DO NOT WANT TO KILL YOUR OWN CREW. Warm up the guns.
If they withdraw their crew to the medbay - fire your lasers at the medbay.
If your crew is losing the fight - teleport them out THEN fire your lasers at the room. With a little luck, this should finish off their crew AND guns.
Alternative Rock Boarding Plan:
If you gain 2 rock crews - you should start making use of Fire Bombs.
Fire a bomb in their gun bay - if a fire starts - teleport your rock in.
Now they can't repair. Warm up your triple lasers for the eventual escape towards their medbay or whatever room the enemy crew want to take refuge in once their wounds are too heavy to continue fighting.
End game
I usually end up with max crew and max energy by sector 8.
Defenses
Shield 3 is good enough. 4 is excellent - but your engine is what's keeping it running.
Engine at 40% evade is great.
Drone Defense I is sufficient. Don't sweat the Boarding Drone too much - they're not what you dreamed of. They can't be targeted and they do their own thing.
Cloak Rank 1 is sufficient. Any higher and you risk longer cooldowns.
Offense
Weapons Power at 5.
3 Basic Lasers & 1 Fire Bomb is good enough
I've had games where I lucked out and found Ion Cannon (CD 4 sec) that can be spammed and drop shields, otherwise... FB is all you need. So stock up on missiles like crazy. You only need 10+ drones.
Everything is dependent on your boarding party anyway which is why...
Teleporter Max Rank for 5 second recharge
Stage 1
Teleport your crew to the their missile launcher (3rd from left)
Firebomb the three-laser turret (2nd from left) if you have spare crew, consider throwing another to the ion cannon (1st from left)
Now, watch for trouble.
Their initial volley of 3-laser and 3-missiles can be avoided by cloak. But the 2nd one you're gonna have to bust out the defensive drone to intercept missiles while the cloak recharges.
Once the two biggest trouble are taken down. Teleport the away team to wreck the ion cannon.
You can safely ignore the beam cannon. They cannot pierce your shields.
Now it's bonus stage.
Bring back the crew, and heal up.
Alt tab, play Mass Effect 2 OST: Suicide Mission
Your objective is to kill as many crew as possible in the main body of the ship. Be aware that they have blast doors. So don't split your teams if you're beaming in two. (Yes, you should beam in your entire team. The enemy flagship is unable to mount ANY offense since you've taken down all shield disabling guns.)
Make sure your missile count is high enough (20+) else the 2nd stage is going to be a bitch.
Board the room furthest from the medbay. Beam a second team to that room to aid in the fight asap. (You DID upgrade teleporter to rank 3 didn't you?)
Once you notice a few of them started retreating to medbay > Fire Bomb the medbay.
Fire bomb the shield bay and laser up to quicken things.
MAKE SURE YOU PULL OUT YOUR TEAM before the flagship explodes.
Stage 2
Now the real fight begins.
If you did everything right, the main body of the flagship should be devoid of crew. So are their two turrets.
Initially, beam your away team to silence their guns first. The missiles do the most damage. Followed by the tri-laser.
You should realize the flagship is starting to utilize boarding drones. The issue isn't their attack, but the hull-pierce effect. If they break into your cockpit and fucking asphyxiate your pilot, you're pretty much forced to deal with it ASAP.
So Firebomb the drone bay while your crew wreck the turrets. Alternatively, you can let your away team deal with the boarding drones, but that's a suboptimal way to deal with the problem.
Spam Defense Drone to intercept boarding drones.
Cloak when the power surge effect occurs. You may want to cloak on the first tri-missle volley - just in case it fucks up your system.
Once the drone and guns are silenced (again, ignore the beam) the only threat is the power surge.
No trouble. Fire bomb the shield generator and spam laser till it's dead.
Stage 3
Victory is assured. I'm sure you know how to deal with the rest.
Once all the crew is dead, the ship would start auto repairing things.
This should clue you on how best to deal with the two turrets.
Beam one team each to the two turrets. They will stay there indefinitely while you firebomb the shit out of their systems, starting with the shields.
Spam the Basic Laser barrage.
You've won Commander.