Mass Effect 3 special edition is one of the Wii U's best games especially online wise. So I've decided to give six character class setups that I have found work well. Point out though these characters are all unlockable ones and you may have to unlock one or all before using but I going to give tips in this post that can help with any character as well.
Adept: Drell
Drell has three powers and two buff stats which all characters have. I have found when setting up any character to focus the most on one power and then lightly fill in the others while also maxing out the buffs
For the Drell I recommend going 6 points on it's reave power. Reave steals health from enemies and gives it to you. It also has a great ability to light up enemies then follow up with your second power pull. When an enemy has been hit with reave and pull together it causes a biotic explosion. Cluster grenades I have found not that effective on higher difficultly. So only give them three points. Your two buffs one increases offense while other defense, on the offense add as much power attack strengh as possible and some weapon damage, on defense spend all ranks on health and shields.
Weapons
I use the m-12 locust smg and the m-5 phalanx pistol, the idea is being as light as possible to have faster power use. The heavier your weapon loadout the slower your power recharge.
Solider
Turian
Turians have two possible setups that both work well depending on your style. First is more in your face offense with the concussive shot. The second is being more sealthy with the proximity mine. Now me personally I like the concussive shot style which the way you can use it effective is attack with your rifle or shotgun after hitting enemies with it since it knocks them down and stuns them. Proximity mine is used to create traps for enemies, aim towards the ground near enemies and when in its range it goes boom. Now on your buffs you want to focus more on weapon damage this time and as always health and shields
Weapons
The Phaeston and M-23 katana
Obviously you are going heavier here and the guns do more of your work then in the adept where it's power based
Engineer
Geth
Engineer is the class that uses tech for butt kicking and this robot character is no different. The setup involves really one power your sentry turret. This turret will get most of your kills for you using its flamethrower. Boost power strengh and health and shields.
Weapons
You really can't go wrong because the turret doesn't have a power recharge like Dwell powers so can go heavy or light.
I use the Phaeston and the M-97 viper sniper rifle
Sentinel
My favorite character the Batarian
Submission Net captures your enemies then you shoot them, blade armor increases your already high health rating, and lastly shockwave allows you to do a biotic explosion to those trapped in the net. Balance both weapon and power buffs and i know broken record but health and shields
Weapons
I go light i use the light weight assualt rifle M-15 vindicator and the M-12 locust smg
Infiltrator
Quarian
Sticky grenades and sabotage. Sticky grenades as they suggest stick to targets and go boom they are weaker then some of the other grenade types in the game though. Sabotage is useless against most enemies but against the robotic race Geth it causes them to cease attacking you and turning on each other. Boost weapons and health and shields
M-97 viper sniper rifle and M-12 locust
Vanguard
Asari
Biotic charge sends you forward to enemies causing damage and status traps them like the submission net mentioned earlier you can use both to biotic explosion. Power boosts and you know by now.
Weapons
M-12 locust and M-5 Phalanx