The Air Raider is useful for all the vehicles. The vehicle controls in this game are the absolute worst you will ever have the displeasure of experiencing but you will need to use them in certain missions. The best vehicles are the mechs with the dual flamethrower cannons and machine guns, rail gun tank, and SAM launcher. He can also call down airstrikes and mortar strikes to clear out large number of bugs too but just make sure you're at a safe distance.

I haven't played the Wing Diver much but there's a super OP weapon called the Chainsaw Laser or something like that and its a must have for that class. I was going through the game with a Wing Diver but stopped playing it.

For the Ranger class, equip the best rocket launcher and grenade launcher that you have. The machine guns and shotguns are useless. There's some dumb and hilarious weapons the Ranger can get too, like a giant grenade with a skull on it that's basically a mini nuke but I'd stick with the launchers. There's some good ones too like the FORK, Air Tortoise, and Stingers.

As for the last class, I never really used it because I hated how slow the guy moves. I main the Air Raider while my friend mains the Ranger class. We got to mission 92 I think before we stopped playing for whatever reason. This game is insanely fun but it can be frustrating sometimes too, especially in those later missions.

Leading the NPCs into battle while singing the EDF theme song makes this fuckin' game so damn good. My stream from last year.