A decent strategy against gamma king for two players. Bring the ice and forest titans (gamma should be enough), and two meks (preferably over lv 280) both equipped with high-quality M.R.L.M. modules (preferably journeyman or better, and take at least 50 pieces of ammo). Whistle attack my target to both titans, and each player mounts a mek. When the king titan has been rendered, get the titans to confront it and drive the meks around (keep hunting for the back), shoot it with the rocket pod or the pistol (be aware of the meteor shower). The gamma king would be taken down in less than 20 minutes under this stratey.