Character: Admonisher for both has been what has worked best but feel free to experiment.
Things to know beforehand: -Generally you want to kill minions with the M60 and bosses with the minigun except Mafia and Curse. -Enemies on small stages with immediate boss spawns (Overtkill, Vaporizer) should be killed with the minigun to save time. -If you run out of ammo in the minigun you wont get it back until you die which will cost you time. -Die as little as possible to stop from costing you time and try to not to run out of ammo in the minigun. -5 kills cause a boss to spawn early. -on Penalty Time 0 you will add 8 secs to your time for every death. -The Minigun will stunlock all Bosses except Mafia.
Mafia 1P Should kill the enemy to the right of them by jumping and shooting with the m60 and 2P should kill enemies to the left until Mafia appears. One player should punch mafia and the other should try to hit him again while he tumbles. Mafia will be susceptible to a second punch for a short time after the first. 12-15 Secs are good times here.
Curse 1P should kill the enemy to their right and 2P should kill the left, either one can get the center one, then move forward into the next room and have one player kill the soldiers and the other wait for curse to spawn after which the waiting player should punch him into the explosive crates and 2P should try to attack him before he becomes invincible during his recovery. 12-15 Secs.
Vandalizer Both players should target him and shoot him as fast as possible with the minigun. Around 4 Secs is a good time here.
Cy-Gor Have 1P kill the wolf behind them and then the wolf to the left while 2p should kill 3 enemies on the right. After 1P deals with their enemies they should run up to the higher area and wait for Cy-gor to spawn, once he does 1P will stun lock him by shooting him and 2P will catch up and help finish him off. Use M60 on enemies and minigun on Cy-gor. This can be done in 11 Secs.
Admonisher One player should kill 2-3 enemies in the spawn room and the other should kill enemies after dropping down the hole to the room with lava. When Admonisher spawns both players should unload with the minigun. 15 secs is a decent time here.
Overtkill Both players will have an enemy to the right of them they should kill them and then shoot Overtkill before he can take any actions. Being to slow could cost you this stage. 4-5 secs is good one this one.
Vindicator Both players will have enemies in their immediate vicinity, one should kill 2 and the other should kill 3. After the player who kills 2 finishes they should go to the main area where Vindicator spawns and stun lock him once he does. The other player will meet up and open fire after they lock on to the boss so they other doesn't run out of ammo. 15 Secs is decent here.
Black Brimstone 1P should kill the enemies in the cave behind them and get ready for brimstone to spawn. Once 2P has killed 3 enemies they should meet 1P at brimstone's spawn site. 15 secs is great on this one.
Vaporizer Both players will have enemies near them that will need to be killed before they can target Vaporizer. Then lock on to him and kill him with the minigun. 6 Secs is a good time here.
Vacillator Both players should run straight ahead and one should stop in the 2nd room to kill the 2 spawning enemies as the other waits in the 3rd room to kill enemies and wait for Vacillator to spawn. Can be killed under 20 Secs.
Gate Keeper Ok this guy is one of the 2 toughest stages. Basically 1P and 2P should make their way out of the cave and try to stun lock Gate Keeper after he spawns and jumps down to the lower level. He will jump down on to the right side of where 1P exits the cave and straight and to the right of where 2P exits. Tough one but can be done in less then 40 secs with a good run.
Angel Teneres Hands down the worst stage with no real strat for it. This one can be done in around 30 secs when your lucky but basically you should try to keep angels off one player while the other shoots Teneres after she spawns. Expect to die on this one. 32 secs is the best time I've seen on this, check square_wave's video on this one.
Dark Ages Spawn Lock on and mow him down with the minigun. Skeletons should not present an issue. 4-5 Secs.
Malebogia The big baddy of the Spawn comics is another of the easy stages. all you have to do is make your way forward far enough for your bullets to him it when you jump. It should take about 5 secs to do this stage.