I always win games like 3v3 shared with this stratgie

What you want to do is first get all the drones until you get the first overlord and then make more drones some to make extractor/minerals and especially to make anoother hatchery next to the one u have. Then you make 3 extractor's because obviously zerg need gas, and put 3 drones for each extractor.

As you have enough money make lots of hatchery's in nice orderly fashion and make 3 spires 2 for upgrading and 1 for greater spire, then double click on larva, and it will hightlight 12 larvas press mutalisk alot of them.

And as you go on hoping you have some really good allies and you have about 34 mutalisk make them into guardians/devourer and more mutalisk especially, then you could wait after they are all done and let your gas go up a liitle. Then if your allie is using battle cruisers send them all up from left/right side and start sweeping drones out like it was a bad memory!

CreepColony's Opinion: Massing air requires a lot of resources, so I guess this is only for $$$ maps.