After you have reached at least level 10 with your main Titans and you have the time, create two sets of Titans to use for attacks. Because Titans require rest time after attacking, you can use your other set to continue. Consider teaming Havok and Tokin, with Apollo or Gadget. Keep Havok and Tokin in battle at all times and use Gadget instead of Apollo when a ranged unit will give you an advantage.