Our general strategy tends to go like this:
1. Start of game, figure out who has which types of cards. Find
somebody who has lots of "C" Action cards to wiggle the computer mouse
2. When the first threat(s) are revealed, players decide to be
responsible for that threat or not. For example, if a player has no
"A" action cards, they would say that they can't help against a
particular threat
3. Usually the player with the battlebots and "C" Card(s) gets stuck
dealing with Internal Threats. These are usually the most problematic
if they show up in the first couple turns since it takes at least 3
turns to activate the Battle Bots and then go to where the Threat is.
Keeping track of the location of internal threats is still something
we have problems with.
Basically, the default action is to do nothing, or maybe replenish the
shields/generators. When a new threat is revealed, 1 or more players
should claim responsibility for it, and the other players should
pretend like that threat doesn't exist. Too many people worrying
about 1 threat tends to cause overkill, and then some other threat
gets through.
When all else fails, fire a bunch of rockets or keep activating the
lower level cannons (the ones with the yellow battery cube). Or
alternate between firing the Pulse Cannon and refilling the central
generator.