Use flare guns to your advantage. Spotting through clouds isn't the only thing they can do. They also put a 15(?)-stack of fire on whatever they hit. That's huge. Combined with their ridiculous arc, they can actually be used as pretty deadly weapons. An otherwise useless side gun (e.g. either side gun on the Spire, rear left gun on close range Pyra) can be transformed into an extra front gun, pretty much. If you target the balloon, then it'll start dying pretty quickly, which'll distract an enemy engineer who would otherwise be firing back. Of course, this can only be pulled off when the main engineer has time to jump on the gun, or when a gunner/gungineer is waiting for a reload. This makes it a deadly combo with a hwacha on a Spire.