The ships need to come with all their weapon slots available, even if that means the initial price per ship is increased, because a new ship without its weapon slots = 100% useless. I bought the final ship with still 3 levels to go and never once was it worth using because of the upgrades needed, so I stuck with the helicopter until the end. Still a very fun game and well worth playing.
The first time I completed it (and didn't have all PIPs) I didn't get the badge. I completed it a second time with all PIPs and got it, hope this helps.
I would like this a lot better if it weren't for the monumental stupidity of the other party members AI. Either they need better abilities to make up for the fact that they're idiots or the player needs to be able to control them.
What works best against the M.O.A.B.? I do just fine in hard mode up until level 37, then all 50 of my lives get wiped out on that one level. So far I've been using mostly tack shooters and cannons (fully upgraded).
 "Notebook Wars 2"){kind=icon}
 "Harry Quantum: TV Go Home"){kind=icon}
 "Escape #4: The Bathroom"){kind=icon}
 "Doodle God"){kind=icon}
 "William and Sly"){kind=icon}
 "Shore Siege!"){kind=icon}
 "Sonny 2"){kind=icon}
 "me and the key"){kind=icon}
 "Pandemic 2"){kind=icon}
 "Bloons Tower Defense 3"){kind=icon}